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VulnerabilityPublished Updated

CVE-2026-100797: Mozilla Firefox · Use After Free

Affects Mozilla FirefoxSource CVE Database V5

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Not known to be exploited · CVSS 8.8 High.

Data as of 13 Nov 2026, 23:53 UTC

CVSS 3.1 base score
8.8High
How severe the flaw is on the 0–10 CVSS scale.
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:H

Exploitation evidence

  1. Disclosed: evidence found.

    CVE published 29 Sep 2026

  2. Detectable: no evidence on record.

    No public nuclei template indexed

  3. Weaponized: no evidence on record.

    No public exploit code indexed in Metasploit or Exploit-DB

  4. Exploited in the wild: no evidence on record.

    Not in CISA KEV and no source reports exploitation

  5. Observed by OffSeq 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

ProductAffectedFixed in
Mozilla FirefoxAffected
  • <115.42
  • <140.17
  • <153.4
  • <157
Fixed in
  • 115.42
  • 140.17
  • 153.4
  • 157

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

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