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VulnerabilityPublished Updated

CVE-2026-6747: Mozilla Firefox · Use After Free

Affects Mozilla FirefoxSource CVE Database V5

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Not known to be exploited · CVSS 7.5 High · patch available : patch Mozilla Firefox soon.

Data as of 30 Oct 2026, 11:52 UTC

CVSS 3.1 base score
7.5High
How severe the flaw is on the 0–10 CVSS scale.
EPSS
0.4% chance of exploitation in 30 days – higher than 34% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.
Patch
Available
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

Exploitation evidence

  1. Disclosed: evidence found.

    CVE published 21 Apr 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
  • <150
Fixed in
  • 150

AI-suggested

Mozilla has released official fixes for this vulnerability in Firefox 150 and Firefox ESR 140.10. Users and administrators should update affected Firefox versions to 150 or later, or Firefox ESR 140.10 or later, to remediate this issue. Since this is not a cloud service, patching the client software is required. No additional mitigation steps are indicated by the vendor advisories.

Description

Use-after-free in the WebRTC component. This vulnerability was fixed in Firefox 150, Firefox ESR 140.10, Thunderbird 150, and Thunderbird 140.10.

References

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