CVE-2025-8027VulnerabilityPublished 11 Aug 2025Updated 28 Jun 2026

Red Hat Security Advisory: thunderbird security update

Affects Red Hat thunderbirdSource GCVE Database

Mentioned vulnerabilities

Authoritative record:CVE-2025-8027· Medium 6.5

Not known to be exploited · CVSS 6.5 Medium.

Data as of 26 Oct 2026, 14:05 UTC

CVSS 3.1 base score

6.5Medium

How severe the flaw is on the 0–10 CVSS scale.

EPSS: 0.4% chance of exploitation in 30 days – higher than 37% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.

CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:N/A:N

Attack Vector: Network
Attack Complexity: Low
Privileges Required: None
User Interaction: Required
Scope: Unchanged
Confidentiality: High
Integrity: None
Availability: None

Bold values are the worst case: easiest to exploit or largest impact.

Attack Vector: Network: The vulnerable component is bound to the network stack and the set of possible attackers extends beyond the other options listed, up to and including the entire Internet. Such a vulnerability is often termed 'remotely exploitable' and can be thought of as an attack being exploitable at the protocol level one or more network hops away (e.g., across one or more routers).
Attack Complexity: Low: Specialized access conditions or extenuating circumstances do not exist. An attacker can expect repeatable success against the vulnerable component.
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: Required: Successful exploitation of this vulnerability requires a user to take some action before the vulnerability can be exploited.
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: High: There is total loss of confidentiality, resulting in all resources within the impacted component being divulged to the attacker. Alternatively, access to only some restricted information is obtained, but the disclosed information presents a direct, serious impact.
Integrity: None: There is no loss of integrity within the impacted component.
Availability: None: There is no impact to availability within the impacted component.

Definitions: FIRST CVSS v3.1 specification.

Exploitation evidence

Disclosed: evidence found.
CVE published 22 Jul 2025
Detectable: no evidence on record.
No public nuclei template indexed
Weaponised: 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 26 Oct 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.
Weaponised: Public exploit code exists in Metasploit or Exploit-DB, 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

Affected software

Product	Affected	Fixed in
Red Hat Product Security Red Hat	Affected Red Hat Red Hat Enterprise Linux Red Hat Enterprise Linux AppStream EUS (v.9.4) src thunderbird-0:128.13.0-3.el9_4.src	Fixed in–

AI-suggested

Red Hat has released updated Thunderbird packages for Red Hat Enterprise Linux 9.4 Extended Update Support that address all identified vulnerabilities. Users should apply these official updates promptly to remediate the security issues. For detailed update instructions, refer to the Red Hat advisory at https://access.redhat.com/articles/11258. No additional mitigations are specified beyond applying the vendor-provided patches.

Description

Mozilla Thunderbird is a standalone mail and newsgroup client. Security Fix(es): * firefox: thunderbird: Large branch table could lead to truncated instruction (CVE-2025-8028) * firefox: thunderbird: Memory safety bugs (CVE-2025-8035) * firefox: thunderbird: Incorrect URL stripping in CSP reports (CVE-2025-8031) * firefox: thunderbird: JavaScript engine only wrote partial return value to stack (CVE-2025-8027) * firefox: thunderbird: Potential user-assisted code execution in ?Copy as cURL? command (CVE-2025-8030) * firefox: Memory safety bugs (CVE-2025-8034) * firefox: thunderbird: Incorrect JavaScript state machine for generators (CVE-2025-8033) * firefox: thunderbird: XSLT documents could bypass CSP (CVE-2025-8032) * firefox: thunderbird: javascript: URLs executed on object and embed tags (CVE-2025-8029) For more details about the security issue(s), including the impact, a CVSS score, acknowledgments, and other related information, refer to the CVE page(s) listed in the References section.

Impact

The vulnerabilities include memory safety bugs that could lead to crashes or potentially exploitable conditions, incorrect handling of URLs in security policies that could weaken protections, and flaws in the JavaScript engine that may allow partial data corruption or user-assisted code execution. These issues could allow attackers to execute arbitrary code or bypass security controls in the context of the Thunderbird mail client, increasing the risk of compromise or data exposure. The Red Hat advisory rates the overall impact as important, reflecting significant but not critical risk.

CWE-457Use of Uninitialized Variable (opens in a new tab)
Variant weaknessLikelihood of exploit: High
The code uses a variable that has not been initialized, leading to unpredictable or unintended results.
Implementation · Attack Surface Reduction
Ensure that critical variables are initialized before first use.
Build and Compilation · Compilation or Build Hardening
Most compilers will complain about the use of uninitialized variables if warnings are turned on.
Implementation · Operation
When using a language that does not require explicit declaration of variables, run or compile the software in a mode that reports undeclared or unknown variables. This may indicate the presence of a typographic error in the variable's name.
From MITRE CWE, MITRE CAPEC and OWASP (Top 10, OpenCRE).
CWE-1332Improper Handling of Faults that Lead to Instruction Skips (opens in a new tab)
Base weakness
The device is missing or incorrectly implements circuitry or sensors that detect and mitigate the skipping of security-critical CPU instructions when they occur.
Architecture and Design
Design strategies for ensuring safe failure if inputs, such as Vcc, are modified out of acceptable ranges.
Architecture and Design
Design strategies for ensuring safe behavior if instructions attempt to be skipped.
Architecture and Design
Identify mission critical secrets that should be wiped if faulting is detected, and design a mechanism to do the deletion.
Attack patterns
Mobile Device Fault Injection (opens in a new tab)
Hardware Fault Injection (opens in a new tab)
From MITRE CWE, MITRE CAPEC and OWASP (Top 10, OpenCRE).
CWE-80Improper Neutralization of Script-Related HTML Tags in a Web Page (Basic XSS) (opens in a new tab)
Variant weaknessLikelihood of exploit: HighOWASP Top 10 A05:2025: Injection (opens in a new tab)
The product receives input from an upstream component, but it does not neutralize or incorrectly neutralizes special characters such as "<", ">", and "&" that could be interpreted as web-scripting elements when they are sent to a downstream component that processes web pages.
Implementation
Carefully check each input parameter against a rigorous positive specification (allowlist) defining the specific characters and format allowed. All input should be neutralized, not just parameters that the user is supposed to specify, but all data in the request, including hidden fields, cookies, headers, the URL…
Implementation · Output Encoding
Use and specify an output encoding that can be handled by the downstream component that is reading the output. Common encodings include ISO-8859-1, UTF-7, and UTF-8.
Implementation
With Struts, write all data from form beans with the bean's filter attribute set to true.
OWASP Cheat Sheets
Abuse Case (opens in a new tab)
Deserialization (opens in a new tab)
Cross Site Scripting Prevention (opens in a new tab)
DOM based XSS Prevention (opens in a new tab)
Injection Prevention (opens in a new tab)
OWASP ASVS 4.0.3
V1.5.1 (opens in a new tab)
V5.3.3 (opens in a new tab)
Attack patterns
XSS Targeting Non-Script Elements (opens in a new tab)
PHP Remote File Inclusion (opens in a new tab)
XSS Through HTTP Query Strings (opens in a new tab)
XSS Through HTTP Headers (opens in a new tab)
From MITRE CWE, MITRE CAPEC and OWASP (Top 10, OpenCRE).
CWE-94Improper Control of Generation of Code ('Code Injection') (opens in a new tab)
Base weaknessLikelihood of exploit: MediumCWE Top 25 (2025): #10OWASP Top 10 A05:2025: Injection (opens in a new tab)
The product constructs all or part of a code segment using externally-influenced input from an upstream component, but it does not neutralize or incorrectly neutralizes special elements that could modify the syntax or behavior of the intended code segment.
Architecture and Design · Refactoring
Refactor your program so that you do not have to dynamically generate code.
Architecture and Design
Run your code in a "jail" or similar sandbox environment that enforces strict boundaries between the process and the operating system. This may effectively restrict which code can be executed by your product.
Implementation · Input Validation
Assume all input is malicious. Use an "accept known good" input validation strategy, i.e., use a list of acceptable inputs that strictly conform to specifications. Reject any input that does not strictly conform to specifications, or transform it into something that does.
OWASP Cheat Sheets
Server Side Request Forgery Prevention (opens in a new tab)
Unvalidated Redirects and Forwards (opens in a new tab)
Cross Site Scripting Prevention (opens in a new tab)
DOM based XSS Prevention (opens in a new tab)
Abuse Case (opens in a new tab)
OWASP ASVS 4.0.3
V5.2.8 (opens in a new tab)
V5.2.5 (opens in a new tab)
V1.5.1 (opens in a new tab)
Attack patterns
Leverage Executable Code in Non-Executable Files (opens in a new tab)
Manipulating User-Controlled Variables (opens in a new tab)
Code Injection (opens in a new tab)
From MITRE CWE, MITRE CAPEC and OWASP (Top 10, OpenCRE).
CWE-276Incorrect Default Permissions (opens in a new tab)
Base weaknessLikelihood of exploit: MediumOWASP Top 10 A01:2025: Broken Access Control (opens in a new tab)
During installation, installed file permissions are set to allow anyone to modify those files.
Architecture and Design · Operation
The architecture needs to access and modification attributes for files to only those users who actually require those actions.
Architecture and Design · Separation of Privilege
Compartmentalize the system to have "safe" areas where trust boundaries can be unambiguously drawn. Do not allow sensitive data to go outside of the trust boundary and always be careful when interfacing with a compartment outside of the safe area.
OWASP Cheat Sheets
Access Control (opens in a new tab)
Authorization Testing Automation (opens in a new tab)
Authorization (opens in a new tab)
OWASP ASVS 4.0.3
V8.3.8 (opens in a new tab)
V13.4.2 (opens in a new tab)
Attack patterns
Accessing Functionality Not Properly Constrained by ACLs (opens in a new tab)
Directory Indexing (opens in a new tab)
Web Server Logs Tampering (opens in a new tab)
From MITRE CWE, MITRE CAPEC and OWASP (Top 10, OpenCRE).
CWE-693Protection Mechanism Failure (opens in a new tab)
Pillar weaknessOWASP Top 10 A06:2025: Insecure Design (opens in a new tab)
The product does not use or incorrectly uses a protection mechanism that provides sufficient defense against directed attacks against the product.
MITRE discourages mapping vulnerabilities to this broad entry; the root cause is usually a more specific weakness.
OWASP Cheat Sheets
Secure Design Principles (opens in a new tab)
Attack patterns
Accessing Functionality Not Properly Constrained by ACLs (opens in a new tab)
Cross Site Tracing (opens in a new tab)
Directory Indexing (opens in a new tab)
Using Malicious Files (opens in a new tab)
Encryption Brute Forcing (opens in a new tab)
From MITRE CWE, MITRE CAPEC and OWASP (Top 10, OpenCRE).
CWE-476NULL Pointer Dereference (opens in a new tab)
Base weaknessLikelihood of exploit: MediumCWE Top 25 (2025): #13OWASP Top 10 A10:2025: Mishandling of Exceptional Conditions (opens in a new tab)
The product dereferences a pointer that it expects to be valid but is NULL.
Implementation
For any pointers that could have been modified or provided from a function that can return NULL, check the pointer for NULL before use. When working with a multithreaded or otherwise asynchronous environment, ensure that proper locking APIs are used to lock before the check, and unlock when it has finished.
Requirements
Select a programming language that is not susceptible to these issues.
Implementation
Check the results of all functions that return a value and verify that the value is non-null before acting upon it.
OWASP Cheat Sheets
Logging (opens in a new tab)
Error Handling (opens in a new tab)
OWASP ASVS 4.0.3
V11.1.7 (opens in a new tab)
From MITRE CWE, MITRE CAPEC and OWASP (Top 10, OpenCRE).
CWE-119Improper Restriction of Operations within the Bounds of a Memory Buffer (opens in a new tab)
Class weaknessLikelihood of exploit: High
The product performs operations on a memory buffer, but it reads from or writes to a memory location outside the buffer's intended boundary. This may result in read or write operations on unexpected memory locations that could be linked to other variables, data structures, or internal program data.
MITRE discourages mapping vulnerabilities to this broad entry; the root cause is usually a more specific weakness.
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
XML Security (opens in a new tab)
Mass Assignment (opens in a new tab)
OWASP ASVS 4.0.3
V13.3.1 (opens in a new tab)
V5.1.4 (opens in a new tab)
V5.1.3 (opens in a new tab)
Attack patterns
Buffer Overflow via Environment Variables (opens in a new tab)
Overflow Buffers (opens in a new tab)
Client-side Injection-induced Buffer Overflow (opens in a new tab)
Filter Failure through Buffer Overflow (opens in a new tab)
MIME Conversion (opens in a new tab)
From MITRE CWE, MITRE CAPEC and OWASP (Top 10, OpenCRE).

References

Community reviews

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Exploitation evidence

What to do

Affected software

Description

AI analysisMachine-generated, updated 25 Jun 2026, 06:02 UTC

WeaknessesCWE-457, CWE-1332, CWE-80 +5

Technical details

References

Community reviews

Related threats