CVE-2026-100797: Mozilla Firefox · Use After Free
Affects Mozilla FirefoxSource CVE Database V5
Not known to be exploited · CVSS 8.8 High.
Data as of 13 Nov 2026, 23:53 UTC
- EPSS
- 0.2% chance of exploitation in 30 days – higher than 16% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.
CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/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
Mozilla has released official fixes for this vulnerability in Firefox ESR 153.4, Firefox 157, Thunderbird 140.17, Thunderbird 153.4, and Thunderbird 157. Users and administrators should update to these versions or later to remediate the issue. No additional mitigation is required once updated.
Description
CVE-2026-100797 is a high-severity privilege escalation vulnerability in Mozilla Firefox caused by a use-after-free flaw in the Graphics: WebRender component. This issue allows an attacker to escalate privileges by exploiting memory corruption. The vulnerability has been fixed in multiple Mozilla products, including Firefox ESR 153.4, Firefox 157, and Thunderbird versions 140.17, 153.4, and 157.
References
- bugzilla.mozilla.org/show_bug.cgi?id=2050542 (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/mfsa2026-98/ (opens in a new tab)
- mozilla.org/security/advisories/mfsa2026-99/ (opens in a new tab)
- mozilla.org/security/advisories/mfsa2026-101/ (opens in a new tab)
- mozilla.org/security/advisories/mfsa2026-102/ (opens in a new tab)
- mozilla.org/security/advisories/mfsa2026-103/ (opens in a new tab)