VulnerabilityPublished 12 Oct 2026Updated 26 Oct 2026

CVE-2026-100832: thunderbird security update

Affects thunderbirdSource GCVE Database

Mentioned vulnerabilities

Authoritative record:CVE-2026-100832· High 8.8

Not known to be exploited · CVSS 8.8 High : upgrade to 140.17.0-1.el10_2.alma.1 soon.

Data as of 26 Oct 2026, 17:16 UTC

CVSS 3.1 base score

8.8High

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

EPSS: 0.2% chance of exploitation in 30 days – higher than 15% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.
Patch: Available – fixed in 140.17.0-1.el10_2.alma.1

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

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

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: High: There is a total loss of integrity, or a complete loss of protection. For example, the attacker is able to modify any/all files protected by the impacted component. Alternatively, only some files can be modified, but malicious modification would present a direct, serious consequence to the impacted component.
Availability: High: There is total loss of availability, resulting in the attacker being able to fully deny access to resources in the impacted component; this loss is either sustained (while the attacker continues to deliver the attack) or persistent (the condition persists even after the attack has completed). Alternatively, the attacker has the ability to deny some availability, but the loss of availability presents a direct, serious consequence to the impacted component (e.g., the attacker cannot disrupt existing connections, but can prevent new connections; the attacker can repeatedly exploit a vulnerability that, in each instance of a successful attack, leaks a only small amount of memory, but after repeated exploitation causes a service to become completely unavailable).

Definitions: FIRST CVSS v3.1 specification.

Exploitation evidence

Disclosed: evidence found.
CVE published 29 Sep 2026
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.

almalinux-10

What to do

Upgrade the AlmaLinux thunderbird package to 140.17.0-1.el10_2.alma.1.

Patches and advisories

access.redhat.com/errata/RHSA-2026:80674 (opens in a new tab)

Affected software

Product	Affected	Fixed in
AlmaLinux 10thunderbird	Affected <140.17.0-1.el10_2.alma.1	Fixed in 140.17.0-1.el10_2.alma.1

Check your own hosts for these packages with threat-finder (opens in a new tab), our free open-source scanner.

Description

Mozilla Thunderbird is a standalone mail and newsgroup client. Security Fix(es): * firefox: thunderbird: Use-after-free in the Graphics: Canvas2D component (CVE-2026-100832) * firefox: Use-after-free in the Layout: Text and Fonts component (CVE-2026-100784) * firefox: thunderbird: Privilege escalation in the DLL Services component (CVE-2026-100801) * firefox: thunderbird: Sandbox escape due to incorrect boundary conditions in the Internationalization component (CVE-2026-100794) * firefox: thunderbird: Privilege escalation in the Address Bar component (CVE-2026-100820) * firefox: thunderbird: Use-after-free in the Graphics: Canvas2D component (CVE-2026-100777) * firefox: thunderbird: Information disclosure in the Networking: JAR component (CVE-2026-100766) * firefox: thunderbird: Use-after-free in the XSLT component (CVE-2026-100779) * firefox: thunderbird: Privilege escalation in the DOM: Service Workers component (CVE-2026-100807) * firefox: thunderbird: JIT miscompilation in the JavaScript: WebAssembly component (CVE-2026-100792) * firefox: Privilege escalation due to use-after-free in the Graphics: WebRender component (CVE-2026-100797) * firefox: thunderbird: Sandbox escape due to incorrect boundary conditions in the XPCOM component (CVE-2026-100819) * firefox: thunderbird: Use-after-free in the JavaScript: WebAssembly component (CVE-2026-100776) * firefox: thunderbird: Use-after-free in the Widget component (CVE-2026-100757) * firefox: Sandbox escape due to use-after-free in the Graphics component (CVE-2026-100786) * firefox: thunderbird: Information disclosure in the Networking component (CVE-2026-96869) * firefox: Sandbox escape due to use-after-free in the DOM: Content Processes component (CVE-2026-100770) * firefox: thunderbird: Use-after-free in the JavaScript: WebAssembly component (CVE-2026-100769) * firefox: Use-after-free in the DOM: Core & HTML component (CVE-2026-100791) * firefox: thunderbird: Sandbox escape due to use-after-free in the Widget: Gtk component (CVE-2026-100818) * firefox: thunderbird: Privilege escalation due to incorrect boundary conditions in the Graphics component (CVE-2026-100782) * firefox: firefox: Sandbox escape via use-after-free in DOM component (CVE-2026-100811) * firefox: thunderbird: Use-after-free in the DOM: Core & HTML component (CVE-2026-100772) * firefox: thunderbird: Uninitialized memory in the Storage: Quota Manager component (CVE-2026-100759) * firefox: Sandbox escape due to use-after-free in the DOM: Core & HTML component (CVE-2026-100778) * firefox: thunderbird: Sandbox escape in the DOM: Navigation component (CVE-2026-100758) * firefox: thunderbird: Sandbox escape in the Graphics component (CVE-2026-100775) * firefox: thunderbird: Sandbox escape due to incorrect boundary conditions in the Graphics: WebRender component (CVE-2026-100781) * firefox: Use-after-free in the DOM: Core & HTML component (CVE-2026-100774) * firefox: thunderbird: Same-origin policy bypass in the WebExtensions component (CVE-2026-100803) * firefox: thunderbird: Use-after-free in the Graphics: Canvas2D component (CVE-2026-100789) * firefox: thunderbird: Use-after-free in the DOM: Core & HTML component (CVE-2026-100785) * firefox: thunderbird: Site isolation issue in the Panning and Zooming component (CVE-2026-100821) * firefox: thunderbird: Invalid pointer in the JavaScript: WebAssembly component (CVE-2026-100788) * firefox: thunderbird: Undefined behavior in the DOM: Streams component (CVE-2026-100771) * firefox: Sandbox escape due to use-after-free in the DOM: Content Processes component (CVE-2026-100762) * firefox: thunderbird: Use-after-free in the XSLT component (CVE-2026-100790) * firefox: thunderbird: Use-after-free in the Storage: IndexedDB component (CVE-2026-100773) * firefox: thunderbird: Use-after-free in the DOM: Core & HTML component (CVE-2026-100780) * firefox: thunderbird: Use-after-free in the Networking: Cache component (CVE-2026-100767) * firefox: thunderbird: Incorrect boundary conditions in the Audio/Video: Playback component (CVE-2026-100756) * firefox: thunderbird: Uninitialized memory in the Audio/Video component (CVE-2026-100783) 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.

References

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