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CVE-2025-6425VulnerabilityPublished Updated

An attacker who enumerated resources from the WebCompat extension could have obtained a persistent UUID that

Source GCVE Database

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Authoritative record:CVE-2025-6425· Medium 4.3

Not known to be exploited · CVSS 4.3 Medium · fixed in 140 : update affected systems when convenient.

Data as of 30 Oct 2026, 01:44 UTC

CVSS 3.1 base score
4.3Medium
How severe the flaw is on the 0–10 CVSS scale.
Patch
Available – fixed in 140, 128.12, 115.25
CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:L/I:N/A:N

Exploitation evidence

  1. Disclosed: evidence found.

    CVE published 24 Jun 2025

  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 29 Oct 2026.

What to do

AI-suggested

This vulnerability has been fixed in Firefox 140 and Firefox ESR 115.25. Users and administrators should update to these versions or later to remediate the issue. No additional mitigation actions are required beyond applying the official updates.

Description

A vulnerability in the WebCompat WebExtension shipped with Firefox allowed an attacker who enumerated its resources to obtain a persistent UUID that identified the browser. This UUID persisted across container tabs and normal/private browsing modes but did not persist across different Firefox profiles. The issue affects Firefox versions prior to 140 and Firefox ESR versions prior to 115.25 and 128.12. The vulnerability has a moderate impact and a CVSS score of 4.3. It was fixed in Firefox 140 and Firefox ESR 115.25.

References

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