CVE-2026-5735
criticalMemory safety bugs present in Firefox 149.0.1 and Thunderbird 149.0.1.
Vendor / product: Mozilla — firefox
Memory safety bugs present in Firefox 149.0.1 and Thunderbird 149.0.1. Some of these bugs showed evidence of memory corruption and we presume that with enough effort some of these could have been exploited to run arbitrary code. This vulnerability was fixed in Firefox 149.0.2 and Thunderbird 149.0.2.
CVSS
9.8
9.8 (CVSS v3.1)
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H Severity source: NVD CVSS v3.1 (nvd@nist.gov)
Timeline (UTC)
Published: 2026-04-07 13:16
Modified: 2026-10-23 23:10
NVD status: Modified
Last synced 2 days ago
Verified against the source API 2026-10-27 07:07 UTC
Exploitation
Not listed in CISA KEV (as of last catalog sync)
Absence from KEV does not mean a CVE is not exploited. Exploitation status: unknown (no authoritative evidence in our sources).
Affected products
mozilla / firefox <149.0.2
mozilla / thunderbird <149.0.2
Weakness classification (CWE)
Source: NVD / CISA. “NVD-CWE-Other” and “NVD-CWE-noinfo” mean NVD could not assign a specific weakness.
Mitigation & advisories
Vendor advisory: https://www.mozilla.org/security/advisories/mfsa2026-25/
References
- https://bugzilla.mozilla.org/buglist.cgi?bug_id=2025475%2C2025477 security@mozilla.org
- https://www.mozilla.org/security/advisories/mfsa2026-25/ security@mozilla.org
- https://www.mozilla.org/security/advisories/mfsa2026-28/ security@mozilla.org
- https://access.redhat.com/security/cve/CVE-2026-5735 0b0ca135-0b70-47e7-9f44-1890c2a1c46c
- https://bugzilla.redhat.com/show_bug.cgi?id=2455904 0b0ca135-0b70-47e7-9f44-1890c2a1c46c
- https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-5735.json 0b0ca135-0b70-47e7-9f44-1890c2a1c46c
Data sources
NVD CVE API 2.0 — fetched 2026-10-27 07:07 UTC · record ↗