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VulnerabilityPublished Updated

CVE-2026-92040: 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 30 Oct 2026, 20:25 UTC

CVSS 3.1 base score
8.8High
How severe the flaw is on the 0–10 CVSS scale.
EPSS
0.4% chance of exploitation in 30 days – higher than 36% 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 15 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 30 Oct 2026.

What to do

Affected software

ProductAffectedFixed in
Mozilla FirefoxAffected
  • <156
Fixed in
  • 156

AI-suggested

Users and administrators should upgrade to Firefox version 156 or later to remediate this vulnerability. The vendor advisory confirms that the issue is fixed in Firefox 156. No additional mitigation actions are required beyond applying this update.

Description

Use-after-free in the JavaScript: WebAssembly component. This vulnerability was fixed in Firefox 156 and Thunderbird 156.

References

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