CVE-2025-6425: firefox Information Disclosure — Fix

Description

An attacker who enumerated resources from the WebCompat extension could have obtained a persistent UUID that identified the browser, and persisted between containers and normal/private browsing mode, but not profiles. This vulnerability was fixed in Firefox 140, Firefox ESR 115.25, Firefox ESR 128.12, Thunderbird 140, and Thunderbird 128.12.

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CVSS v3.1 Score

4.3

MEDIUM

CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:L/I:N/A:N

Weakness Type (CWE)

CWE-200 CWE-200

Affected Products

Vendor	Product	Versions
mozilla	firefox	< 115.25.0
mozilla	firefox	< 140.0
mozilla	firefox	116.0 — 128.12.0

References

Advisories & Patches

https://bugzilla.mozilla.org/show_bug.cgi?id=1717672 https://www.mozilla.org/security/advisories/mfsa2025-51/ https://www.mozilla.org/security/advisories/mfsa2025-52/ https://www.mozilla.org/security/advisories/mfsa2025-53/ https://www.mozilla.org/security/advisories/mfsa2025-54/ https://www.mozilla.org/security/advisories/mfsa2025-55/

Other References

https://lists.debian.org/debian-lts-announce/2025/06/msg00029.html https://lists.debian.org/debian-lts-announce/2025/07/msg00002.html

Frequently Asked Questions

What is CVE-2025-6425? +

An attacker who enumerated resources from the WebCompat extension could have obtained a persistent UUID that identified the browser, and persisted between containers and normal/private browsing mode, but not profiles. This vulnerability was fixed in Firefox 140, Firefox ESR 115.25, Firefox ESR 128.12, Thunderbird 140, and Thunderbird 128.12. It has a CVSS v3.1 base score of 4.3 (MEDIUM).

How severe is CVE-2025-6425? +

CVE-2025-6425 has a CVSS v3.1 score of 4.3 out of 10, rated MEDIUM. This is a medium-severity vulnerability that should be remediated as part of regular maintenance.

What products are affected by CVE-2025-6425? +

CVE-2025-6425 affects products from mozilla, specifically: firefox. Check the affected products table above for specific version ranges.

How do I check if I'm vulnerable to CVE-2025-6425? +

You can use Secably's free Website Scanner to check your website for known vulnerabilities. For infrastructure scanning, use the Port Scanner to identify exposed services that may be affected. Check the vendor advisories linked above for specific patch and version information.

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