Skip to main content
VulnerabilityPublished Updated

CVE-2026-100757: Use After Free

Source GCVE Database

0
Compare
Authoritative record:CVE-2026-100757· High 8.8

Not known to be exploited · CVSS 8.8 High · fixed in 153.4 : patch Firefox soon.

Data as of 12 Nov 2026, 23:24 UTC

CVSS 3.1 base score
8.8High
How severe the flaw is on the 0–10 CVSS scale.
EPSS
0.3% chance of exploitation in 30 days – higher than 25% 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: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

AI-suggested

This vulnerability has been fixed in Firefox ESR 153.4, Firefox 157, Firefox ESR 115.42, and Firefox ESR 140.17. Users and administrators should update to these versions or later to remediate the issue. No additional mitigation steps are required beyond applying the official patches.

Description

CVE-2026-100757 is a use-after-free vulnerability in the Widget component of Firefox. It was fixed in Firefox ESR versions 153.4, 157, 115.42, and 140.17. The vulnerability has a high severity rating with a CVSS score of 8.8, indicating it can lead to significant confidentiality, integrity, and availability impacts. No known exploits in the wild have been reported.

References

Community reviews

Loading reviews…