Red Hat Security Advisory: thunderbird security, bug fix, and enhancement update
Affects Red Hat thunderbird security,Source GCVE Database
Mentioned vulnerabilities
Not known to be exploited · CVSS 2.9 Low →: upgrade Red Hat libexpat to 2.8.1 when convenient.
Data as of 6 Nov 2026, 08:23 UTC
- Patch
- Available – fixed in 2.8.1
CVSS:3.1/AV:L/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:L- Attack Vector
- Local
- Attack Complexity
- High
- Privileges Required
- None
- User Interaction
- None
- Scope
- Unchanged
- Confidentiality
- None
- Integrity
- None
- Availability
- Low
Bold values are the worst case: easiest to exploit or largest impact.
- Attack Vector: Local
- The vulnerable component is not bound to the network stack and the attacker’s path is via read/write/execute capabilities. Either: the attacker exploits the vulnerability by accessing the target system locally (e.g., keyboard, console), or remotely (e.g., SSH); or the attacker relies on User Interaction by another person to perform actions required to exploit the vulnerability (e.g., tricking a legitimate user into opening a malicious document).
- Attack Complexity: High
- A successful attack depends on conditions beyond the attacker's control. That is, a successful attack cannot be accomplished at will, but requires the attacker to invest in some measurable amount of effort in preparation or execution against the vulnerable component before a successful attack can be expected. For example, a successful attack may require an attacker to: gather knowledge about the environment in which the vulnerable target/component exists; prepare the target environment to improve exploit reliability; or inject themselves into the logical network path between the target and the resource requested by the victim in order to read and/or modify network communications (e.g., a man in the middle attack).
- Privileges Required: None
- The attacker is unauthorized prior to attack, and therefore does not require any access to settings or files to carry out an attack.
- User Interaction: None
- The vulnerable system can be exploited without any interaction from any user.
- Scope: Unchanged
- An exploited vulnerability can only affect resources managed by the same security authority. In this case, the vulnerable component and the impacted component are either the same, or both are managed by the same security authority.
- Confidentiality: None
- There is no loss of confidentiality within the impacted component.
- Integrity: None
- There is no loss of integrity within the impacted component.
- Availability: Low
- Performance is reduced or there are interruptions in resource availability. Even if repeated exploitation of the vulnerability is possible, the attacker does not have the ability to completely deny service to legitimate users. The resources in the impacted component are either partially available all of the time, or fully available only some of the time, but overall there is no direct, serious consequence to the impacted component.
Definitions: FIRST CVSS v3.1 specification.
Exploitation evidence
Disclosed: evidence found.
CVE published 10 May 2026
Detectable: no evidence on record.
No public nuclei template indexed
Weaponized: no evidence on record.
No public exploit code indexed in Metasploit or Exploit-DB
Exploited in the wildExploited: no evidence on record.
Not in CISA KEV and no source reports exploitation
Observed by OffSeq MirageSeen by Mirage: no evidence on record.
No attack traffic recorded by OffSeq Mirage sensors
A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), the Metasploit, Exploit-DB and nuclei-templates index as of 5 Nov 2026.
- Disclosed
- The CVE record is public on cve.org. Its publication is t = 0.
- Detectable
- A public nuclei template can find exposed instances, for defenders and attackers alike.
- Weaponized
- A Metasploit exploit module or Exploit-DB entry exists (Metasploit scanner modules do not count), or CISA SSVC or the CVSS exploit maturity reports a public proof of concept.
- Exploited in the wild
- CISA KEV lists it, CISA SSVC rates exploitation active, or a source reports attacks.
- Observed by OffSeq Mirage
- OffSeq Mirage honeypot sensors recorded attack traffic for this CVE, or found exposed hosts without attack traffic.
Moments are spaced evenly, not to scale; a dashed line marks a gap of six months or more. Deltas count from t = 0. Sources that give only a date (CISA KEV, Exploit-DB, or a time of exactly 00:00Z) read “same day” rather than hours. Metasploit modules carry the flaw’s disclosure date, not their release date, and nuclei templates carry no date, so both appear above but not on the timeline.
What to do
Upgrade libexpat and libexpat/libexpat to 2.8.1.
Affected software
| Product | Affected | Fixed in |
|---|---|---|
| libexpat projectlibexpat | Affected
| Fixed in
|
GitHublibexpat/libexpatpkg:github/libexpat/libexpatOther threats | Affected
| Fixed in
|
Check your own hosts for these packages with threat-finder (opens in a new tab), our free open-source scanner.
AI-suggested
Red Hat has released an update for Thunderbird on Red Hat Enterprise Linux 9.6 Extended Update Support that addresses these vulnerabilities. Users should apply this update promptly to remediate the security issues. For detailed instructions on applying the update, refer to the Red Hat advisory at https://access.redhat.com/articles/11258. No additional mitigation steps are indicated beyond applying the official update.
Description
A Red Hat security advisory addresses multiple vulnerabilities in Mozilla Thunderbird and Firefox components, including denial of service, privilege escalation, information disclosure, use-after-free, sandbox escapes, mitigation bypasses, and other security issues. These vulnerabilities affect various components such as XML parsing, application update, DOM, JavaScript engine, networking, graphics, and security policies. The advisory provides an update for Thunderbird on Red Hat Enterprise Linux 9.6 Extended Update Support to fix these issues.
Impact
The vulnerabilities collectively allow attackers to cause denial of service, escalate privileges, disclose sensitive information, bypass security mitigations, and escape sandbox environments. These impacts can compromise the confidentiality, integrity, and availability of the affected systems running Thunderbird and Firefox components. The presence of multiple use-after-free and boundary condition issues increases the risk of memory corruption and potential arbitrary code execution. Privilege escalation and sandbox escape vulnerabilities further increase the threat severity by potentially allowing attackers to gain higher system privileges or break isolation mechanisms.
- CWE-407Inefficient Algorithmic Complexity (opens in a new tab)
Class weaknessLikelihood of exploit: Low
An algorithm in a product has an inefficient worst-case computational complexity that may be detrimental to system performance and can be triggered by an attacker, typically using crafted manipulations that ensure that the worst case is being reached.
- OWASP Cheat Sheets
- OWASP ASVS 4.0.3
From MITRE CWE, MITRE CAPEC and OWASP (Top 10, OpenCRE).
- CWE-266Incorrect Privilege Assignment (opens in a new tab)
Base weaknessOWASP Top 10 A06:2025: Insecure Design (opens in a new tab)
A product incorrectly assigns a privilege to a particular actor, creating an unintended sphere of control for that actor.
Architecture and Design · Operation
Very carefully manage the setting, management, and handling of privileges. Explicitly manage trust zones in the software.
Architecture and Design · Operation · Environment Hardening
Run your code using the lowest privileges that are required to accomplish the necessary tasks. If possible, create isolated accounts with limited privileges that are only used for a single task. That way, a successful attack will not immediately give the attacker access to the rest of the software or its environment.
- OWASP Cheat Sheets
From MITRE CWE, MITRE CAPEC and OWASP (Top 10, OpenCRE).
- CWE-825Expired Pointer Dereference (opens in a new tab)
Base weakness
The product dereferences a pointer that contains a location for memory that was previously valid, but is no longer valid.
Architecture and Design
Choose a language that provides automatic memory management.
Implementation
When freeing pointers, be sure to set them to NULL once they are freed. However, the utilization of multiple or complex data structures may lower the usefulness of this strategy.
- OWASP Cheat Sheets
From MITRE CWE, MITRE CAPEC and OWASP (Top 10, OpenCRE).
- CWE-653Improper Isolation or Compartmentalization (opens in a new tab)
Class weaknessOWASP Top 10 A06:2025: Insecure Design (opens in a new tab)
The product does not properly compartmentalize or isolate functionality, processes, or resources that require different privilege levels, rights, or permissions.
Architecture and Design
Break up privileges between different modules, objects, or entities. Minimize the interfaces between modules and require strong access control between them.
- OWASP Cheat Sheets
From MITRE CWE, MITRE CAPEC and OWASP (Top 10, OpenCRE).
- CWE-908Use of Uninitialized Resource (opens in a new tab)
Base weaknessLikelihood of exploit: Medium
The product uses or accesses a resource that has not been initialized.
Implementation
Explicitly initialize the resource before use. If this is performed through an API function or standard procedure, follow all required steps.
Implementation
Pay close attention to complex conditionals that affect initialization, since some branches might not perform the initialization.
Implementation
Avoid race conditions (CWE-362) during initialization routines.
From MITRE CWE, MITRE CAPEC and OWASP (Top 10, OpenCRE).
- CWE-787Out-of-bounds Write (opens in a new tab)
Base weaknessLikelihood of exploit: HighCWE Top 25 (2025): #5
The product writes data past the end, or before the beginning, of the intended buffer.
Requirements · Language Selection
Use a language that does not allow this weakness to occur or provides constructs that make this weakness easier to avoid.
Architecture and Design · Libraries or Frameworks
Use a vetted library or framework that does not allow this weakness to occur or provides constructs that make this weakness easier to avoid.
Operation · Build and Compilation · Environment Hardening
Use automatic buffer overflow detection mechanisms that are offered by certain compilers or compiler extensions. Examples include: the Microsoft Visual Studio /GS flag, Fedora/Red Hat FORTIFY_SOURCE GCC flag, StackGuard, and ProPolice, which provide various mechanisms including canary-based detection and range/index…
- OWASP Cheat Sheets
From MITRE CWE, MITRE CAPEC and OWASP (Top 10, OpenCRE).
- CWE-843Access of Resource Using Incompatible Type (Type Confusion) (opens in a new tab)
Base weakness
The product allocates or initializes a resource such as a pointer, object, or variable using one type, but it later accesses that resource using a type that is incompatible with the original type.
- CWE-190Integer Overflow or Wraparound (opens in a new tab)
Base weaknessLikelihood of exploit: Medium
The product performs a calculation that can produce an integer overflow or wraparound when the logic assumes that the resulting value will always be larger than the original value. This occurs when an integer value is incremented to a value that is too large to store in the associated representation. When this occurs, the value may become a very small or negative number.
Requirements
Ensure that all protocols are strictly defined, such that all out-of-bounds behavior can be identified simply, and require strict conformance to the protocol.
Requirements · Language Selection
Use a language that does not allow this weakness to occur or provides constructs that make this weakness easier to avoid.
Architecture and Design · Libraries or Frameworks
Use a vetted library or framework that does not allow this weakness to occur or provides constructs that make this weakness easier to avoid.
- OWASP Cheat Sheets
- Attack patterns
From MITRE CWE, MITRE CAPEC and OWASP (Top 10, OpenCRE).
- CWE-346Origin Validation Error (opens in a new tab)
Class weaknessOWASP Top 10 A07:2025: Authentication Failures (opens in a new tab)
The product does not properly verify that the source of data or communication is valid.
- OWASP Cheat Sheets
From MITRE CWE, MITRE CAPEC and OWASP (Top 10, OpenCRE).
- CWE-807Reliance on Untrusted Inputs in a Security Decision (opens in a new tab)
Base weaknessLikelihood of exploit: HighOWASP Top 10 A06:2025: Insecure Design (opens in a new tab)
The product uses a protection mechanism that relies on the existence or values of an input, but the input can be modified by an untrusted actor in a way that bypasses the protection mechanism.
Architecture and Design · Attack Surface Reduction
Store state information and sensitive data on the server side only.
Architecture and Design · Libraries or Frameworks
Use a vetted library or framework that does not allow this weakness to occur or provides constructs that make this weakness easier to avoid.
Architecture and Design
For any security checks that are performed on the client side, ensure that these checks are duplicated on the server side, in order to avoid CWE-602. Attackers can bypass the client-side checks by modifying values after the checks have been performed, or by changing the client to remove the client-side checks…
- OWASP Cheat Sheets
From MITRE CWE, MITRE CAPEC and OWASP (Top 10, OpenCRE).
- CWE-201Insertion of Sensitive Information Into Sent Data (opens in a new tab)
Base weaknessOWASP Top 10 A01:2025: Broken Access Control (opens in a new tab)
The code transmits data to another actor, but a portion of the data includes sensitive information that should not be accessible to that actor.
Requirements
Specify which data in the software should be regarded as sensitive. Consider which types of users should have access to which types of data.
Implementation
Ensure that any possibly sensitive data specified in the requirements is verified with designers to ensure that it is either a calculated risk or mitigated elsewhere.
System Configuration
Setup default error messages so that unexpected errors do not disclose sensitive information.
- OWASP Cheat Sheets
From MITRE CWE, MITRE CAPEC and OWASP (Top 10, OpenCRE).
- CWE-552Files or Directories Accessible to External Parties (opens in a new tab)
Base weaknessOWASP Top 10 A01:2025: Broken Access Control (opens in a new tab)
The product makes files or directories accessible to unauthorized actors, even though they should not be.
Implementation · System Configuration · Operation
When storing data in the cloud (e.g., S3 buckets, Azure blobs, Google Cloud Storage, etc.), use the provider's controls to disable public access.
- OWASP Cheat Sheets
From MITRE CWE, MITRE CAPEC and OWASP (Top 10, OpenCRE).
- CWE-193Off-by-one Error (opens in a new tab)
Base weakness
A product calculates or uses an incorrect maximum or minimum value that is 1 more, or 1 less, than the correct value.
Implementation
When copying character arrays or using character manipulation methods, the correct size parameter must be used to account for the null terminator that needs to be added at the end of the array.
From MITRE CWE, MITRE CAPEC and OWASP (Top 10, OpenCRE).
- CWE-368Context Switching Race Condition (opens in a new tab)
Base weakness
A product performs a series of non-atomic actions to switch between contexts that cross privilege or other security boundaries, but a race condition allows an attacker to modify or misrepresent the product's behavior during the switch.
- OWASP Cheat Sheets
- OWASP ASVS 4.0.3
From MITRE CWE, MITRE CAPEC and OWASP (Top 10, OpenCRE).
- CWE-358Improperly Implemented Security Check for Standard (opens in a new tab)
Base weakness
The product does not implement or incorrectly implements one or more security-relevant checks as specified by the design of a standardized algorithm, protocol, or technique.
- CWE-641Improper Restriction of Names for Files and Other Resources (opens in a new tab)
Base weaknessLikelihood of exploit: Low
The product constructs the name of a file or other resource using input from an upstream component, but it does not restrict or incorrectly restricts the resulting name.
Architecture and Design
Do not allow users to control names of resources used on the server side.
Architecture and Design
Perform allowlist input validation at entry points and also before consuming the resources. Reject bad file names rather than trying to cleanse them.
Architecture and Design
Make sure that technologies consuming the resources are not vulnerable (e.g. buffer overflow, format string, etc.) in a way that would allow code execution if the name of the resource is malformed.
- OWASP Cheat Sheets
- OWASP ASVS 4.0.3
From MITRE CWE, MITRE CAPEC and OWASP (Top 10, OpenCRE).
- CWE-290Authentication Bypass by Spoofing (opens in a new tab)
Base weaknessOWASP Top 10 A07:2025: Authentication Failures (opens in a new tab)
This attack-focused weakness is caused by incorrectly implemented authentication schemes that are subject to spoofing attacks.
- OWASP Cheat Sheets
- Attack patterns
- Creating a Rogue Certification Authority Certificate (opens in a new tab)
- Web Services API Signature Forgery Leveraging Hash Function Extension Weakness (opens in a new tab)
- Signature Spoof (opens in a new tab)
- Signature Spoofing by Misrepresentation (opens in a new tab)
- Session Credential Falsification through Prediction (opens in a new tab)
From MITRE CWE, MITRE CAPEC and OWASP (Top 10, OpenCRE).
- CWE-770Allocation of Resources Without Limits or Throttling (opens in a new tab)
Base weaknessLikelihood of exploit: HighCWE Top 25 (2025): #25
The product allocates a reusable resource or group of resources on behalf of an actor without imposing any intended restrictions on the size or number of resources that can be allocated.
Requirements
Clearly specify the minimum and maximum expectations for capabilities, and dictate which behaviors are acceptable when resource allocation reaches limits.
Architecture and Design
Limit the amount of resources that are accessible to unprivileged users. Set per-user limits for resources. Allow the system administrator to define these limits. Be careful to avoid CWE-410.
Architecture and Design
Design throttling mechanisms into the system architecture. The best protection is to limit the amount of resources that an unauthorized user can cause to be expended.
- OWASP Cheat Sheets
From MITRE CWE, MITRE CAPEC and OWASP (Top 10, OpenCRE).
- CWE-366Race Condition within a Thread (opens in a new tab)
Base weaknessLikelihood of exploit: Medium
If two threads of execution use a resource simultaneously, there exists the possibility that resources may be used while invalid, in turn making the state of execution undefined.
Architecture and Design
Use locking functionality. This is the recommended solution. Implement some form of locking mechanism around code which alters or reads persistent data in a multithreaded environment.
Architecture and Design
Create resource-locking validation checks. If no inherent locking mechanisms exist, use flags and signals to enforce your own blocking scheme when resources are being used by other threads of execution.
- OWASP Cheat Sheets
- OWASP ASVS 4.0.3
From MITRE CWE, MITRE CAPEC and OWASP (Top 10, OpenCRE).
- CWE-359Exposure of Private Personal Information to an Unauthorized Actor (opens in a new tab)
Base weaknessOWASP Top 10 A01:2025: Broken Access Control (opens in a new tab)
The product does not properly prevent a person's private, personal information from being accessed by actors who either (1) are not explicitly authorized to access the information or (2) do not have the implicit consent of the person about whom the information is collected.
Requirements
Identify and consult all relevant regulations for personal privacy. An organization may be required to comply with certain federal and state regulations, depending on its location, the type of business it conducts, and the nature of any private data it handles.
Architecture and Design
Carefully evaluate how secure design may interfere with privacy, and vice versa. Security and privacy concerns often seem to compete with each other. From a security perspective, all important operations should be recorded so that any anomalous activity can later be identified.
Implementation · Operation · Attack Surface Reduction
Some tools can automatically analyze documents to redact, strip, or "sanitize" private information, although some human review might be necessary. Tools may vary in terms of which document formats can be processed.
- OWASP Cheat Sheets
From MITRE CWE, MITRE CAPEC and OWASP (Top 10, OpenCRE).
- CWE-356Name not in the CWE catalogue (opens in a new tab)
- CWE-184Name not in the CWE catalogue (opens in a new tab)
- GCVE source
- db.gcve.eu
- Csaf Category
- csaf_security_advisory
- Csaf Version
- 2.0
- Publisher
- Red Hat Product Security
- Advisory ID
- RHSA-2026:95596
- Vendor Severity
- high
- CVE Count
- 62
- Additional Cves
- CVE-2026-109704, CVE-2026-109705, CVE-2026-109706, CVE-2026-109707, CVE-2026-109708, CVE-2026-109709, CVE-2026-109710, CVE-2026-109711, CVE-2026-109712, CVE-2026-109713, CVE-2026-109715, CVE-2026-109716, CVE-2026-109717, CVE-2026-109718, CVE-2026-109719, CVE-2026-109720, CVE-2026-109721, CVE-2026-109722, CVE-2026-109723, CVE-2026-109724, CVE-2026-109725, CVE-2026-109726, CVE-2026-109727, CVE-2026-109728, CVE-2026-109729, CVE-2026-109730, CVE-2026-109731, CVE-2026-109732, CVE-2026-109733, CVE-2026-109734, CVE-2026-109736, CVE-2026-109737, CVE-2026-109738, CVE-2026-109740, CVE-2026-109741, CVE-2026-109742, CVE-2026-109743, CVE-2026-109744, CVE-2026-109745, CVE-2026-109751, CVE-2026-109752, CVE-2026-109753, CVE-2026-109754, CVE-2026-109756, CVE-2026-109757, CVE-2026-109759, CVE-2026-109760, CVE-2026-109762, CVE-2026-109763, CVE-2026-109764, CVE-2026-109765, CVE-2026-109766, CVE-2026-109767, CVE-2026-109770, CVE-2026-109775, CVE-2026-109776, CVE-2026-109777, CVE-2026-109778, CVE-2026-109781, CVE-2026-109782, CVE-2026-109783
References
- access.redhat.com/errata/RHSA-2026:95596 (opens in a new tab)
- access.redhat.com/security/updates/classification/ (opens in a new tab)
- bugzilla.redhat.com/show_bug.cgi?id=2468575 (opens in a new tab)
- bugzilla.redhat.com/show_bug.cgi?id=2550393 (opens in a new tab)
- bugzilla.redhat.com/show_bug.cgi?id=2550394 (opens in a new tab)
- bugzilla.redhat.com/show_bug.cgi?id=2550396 (opens in a new tab)
- bugzilla.redhat.com/show_bug.cgi?id=2550397 (opens in a new tab)
- bugzilla.redhat.com/show_bug.cgi?id=2550400 (opens in a new tab)
- bugzilla.redhat.com/show_bug.cgi?id=2550401 (opens in a new tab)
- bugzilla.redhat.com/show_bug.cgi?id=2550403 (opens in a new tab)
- bugzilla.redhat.com/show_bug.cgi?id=2550404 (opens in a new tab)
- bugzilla.redhat.com/show_bug.cgi?id=2550405 (opens in a new tab)
- bugzilla.redhat.com/show_bug.cgi?id=2550406 (opens in a new tab)
- bugzilla.redhat.com/show_bug.cgi?id=2550408 (opens in a new tab)
- bugzilla.redhat.com/show_bug.cgi?id=2550410 (opens in a new tab)
- bugzilla.redhat.com/show_bug.cgi?id=2550411 (opens in a new tab)
- bugzilla.redhat.com/show_bug.cgi?id=2550412 (opens in a new tab)
- bugzilla.redhat.com/show_bug.cgi?id=2550413 (opens in a new tab)
- bugzilla.redhat.com/show_bug.cgi?id=2550417 (opens in a new tab)
- bugzilla.redhat.com/show_bug.cgi?id=2550418 (opens in a new tab)
Community reviews
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