CVE-2026-100829: Mozilla Firefox · CWE-693
Affects Mozilla FirefoxSource CVE Database V5
Not known to be exploited · CVSS 9.6 Critical · fixed in 153.4 : patch Mozilla Firefox as a priority.
Data as of 13 Nov 2026, 23:53 UTC
- 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 153.4
CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:H/I:H/A:HExploitation evidence
Disclosed: evidence found.
CVE published 29 Sep 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 13 Nov 2026.
What to do
Affected software
| Product | Affected | Fixed in |
|---|---|---|
| Mozilla Firefox | Affected
| Fixed in
|
AI-suggested
A fix is available and has been released by Mozilla. Users and administrators should update to Firefox ESR 153.4 or Firefox 157 (or later) to remediate this vulnerability. Similarly, Thunderbird users should update to versions 153.4 or 157. No additional mitigation steps are indicated by the vendor advisory.
Description
CVE-2026-100829 is a critical mitigation bypass vulnerability in the DOM security component of Mozilla Firefox. It allows an attacker to bypass security controls, potentially leading to complete compromise of confidentiality, integrity, and availability. The issue has been fixed in Firefox ESR 153.4 and Firefox 157, as well as Thunderbird 153.4 and 157.
References
- bugzilla.mozilla.org/show_bug.cgi?id=2066321 (opens in a new tab)
- mozilla.org/security/advisories/mfsa2026-100/ (opens in a new tab)
- mozilla.org/security/advisories/mfsa2026-97/ (opens in a new tab)
- mozilla.org/security/advisories/mfsa2026-101/ (opens in a new tab)
- mozilla.org/security/advisories/mfsa2026-103/ (opens in a new tab)