Use-after-free in Thunderbird S/MIME decryption during password prompt
Key facts
- Attack vector
- Network
- Privileges required
- Low
- User interaction
- None
- Attack complexity
- Low
- Impact type
- —
- Confidentiality · integrity · availability
- Low · None · Low
- Fix status
- Partial Red Hat: 5 without a fix
Attack profile from CVSS 3.1 · CISA ADP. Fix status from CNA and Red Hat.
Summary
Mozilla Thunderbird builds that predate the fixes in 153.6 and 158.0.1 are affected. When a message load finishes or is cancelled while a security device password prompt is open during S/MIME decryption, the message decoder is freed while still in use (CWE-416). A network attacker with low privileges and no user interaction can trigger a potentially exploitable crash.
Written with Claude Haiku 5.5 from the sources below · 2026-11-06
Description from the CNA
When Thunderbird asked for a security device password (for example a smartcard PIN or the Primary Password) while decrypting an S/MIME message, the message load could finish or be cancelled while the prompt was open. This freed the message decoder while it was still in use, causing a use-after-free and a potentially exploitable crash. This vulnerability was fixed in Thunderbird 158.0.1 and Thunderbird 153.6.
Why it matters now
SSVC decision points
CISA ADP · SSVC 2.0.3
- Exploitation
- None
- Automatable
- No
- Technical impact
- Partial
The decision (Track, Attend, Act) also depends on your mission and well-being impact; see CISA's SSVC guide.
Affected products
Remediation
Mozilla Thunderbird is fixed in versions 153.6 and 158.0.1. Red Hat rates the issue Moderate and lists Red Hat Enterprise Linux 6 and 7 as no fix planned, and Red Hat Enterprise Linux 8, 9 and 10 as none available.
Written with Claude Haiku 5.5 from the sources below · 2026-11-06
- Fix · CNA Thunderbird (Mozilla) Fixed in 153.6, 158.0.1
Vendor assessments
Red Hat
Red Hat rating: Moderate. Red Hat's page for this CVE →
| Product | Status | Plan or fix |
|---|---|---|
| Red Hat Enterprise Linux 10 | Affected | No fix yet |
| Red Hat Enterprise Linux 6 | Affected | No fix planned: Out of support scope |
| Red Hat Enterprise Linux 7 | Affected | No fix planned: Out of support scope |
| Red Hat Enterprise Linux 8 | Affected | No fix yet |
| Red Hat Enterprise Linux 9 | Affected | No fix yet |
Timeline
- 2026-10-20 Threatist record created from CVE-2026-113869
- 2026-10-21 Alias added: GHSA-2xmq-c4ch-m4cp
- 2026-10-21 Affected versions changed · Red Hat
- 2026-10-21 CVSS score added · Red Hat
- 2026-10-27 Fix available: Mozilla/[email protected] · CNA
- 2026-10-27 1 new reference · CNA
- 2026-10-30 Affected versions changed · Red Hat
- 2026-10-30 CVSS score changed · Red Hat
- 2026-11-02 Affected versions changed · Red Hat
- 2026-11-06 Affected versions changed · Red Hat
References
More Mozilla vulnerabilities
- TI-2024-08981 Use after free in Mozilla Firefox KEVCVSS 3.1CRITICAL 9.8
- TI-2022-09832 Use after free in Mozilla Firefox KEVCVSS 3.1CRITICAL 9.6
- TI-2019-08769 Improper input validation in Mozilla Firefox ESR KEVCVSS 3.1CRITICAL 10.0
- TI-2010-03577 Mozilla Firefox 3.5.x through 3.5.14 and 3.6.x through 3.6.11, Thunderbird 3.1.6 before… KEVCVSS 3.1CRITICAL 9.8
- TI-2023-04799 Out-of-bounds write in Google Chrome KEVCVSS 3.1HIGH 8.8
- TI-2023-04477 Out-of-bounds write in Google Chrome KEVCVSS 3.1HIGH 8.8
Sources
- CVE-2026-113869 · CVE Program
- CVE-2026-113869 · NVD
- FIRST EPSS
- GHSA-2xmq-c4ch-m4cp · GitHub Advisory Database · CC BY 4.0
- CVE-2026-113869 · Red Hat security data · CC BY 4.0
This product uses the NVD API but is not endorsed or certified by the NVD. Sources and licences