CVE-2026-109763: Mitigation Bypass
Source GCVE Database
Not known to be exploited · CVSS 5.4 Medium.
Data as of 31 Oct 2026, 00:06 UTC
Thin evidence
One scorer or none| CISA-ADP | CVSS 3.1 | 5.4 |
|---|
CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:L/I:L/A:NExploitation evidence
Disclosed: evidence found.
CVE published 13 Oct 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 30 Oct 2026.
What to do
AI-suggested
Users and administrators should update Firefox to version 158 or later, or Firefox ESR 153.5 or later, to remediate this vulnerability. The vendor advisory confirms that the issue is fixed in these versions. No additional mitigation actions are required beyond applying the official update.
Description
CVE-2026-109763 is a mitigation bypass vulnerability in the File Handling component of Firefox. This issue was addressed and fixed in Firefox version 158 and Firefox ESR 153.5. The vulnerability has a medium severity rating with a CVSS score of 5.4, indicating limited impact on confidentiality and integrity, and no impact on availability. No known exploits in the wild have been reported.
References
- nvd.nist.gov/vuln/detail/CVE-2026-109763 (opens in a new tab)
- bugzilla.mozilla.org/show_bug.cgi?id=2072501 (opens in a new tab)
- mozilla.org/security/advisories/mfsa2026-106 (opens in a new tab)
- mozilla.org/security/advisories/mfsa2026-108 (opens in a new tab)
- mozilla.org/security/advisories/mfsa2026-109 (opens in a new tab)
- mozilla.org/security/advisories/mfsa2026-110 (opens in a new tab)