CVE-2025-6425

Name: CVE-2025-6425
Creator: NVD / NIST
Published: 2025-06-24T13:15:23.403+00:00
License: https://creativecommons.org/publicdomain/zero/1.0/

MEDIUMCVSS 4.3/10EPSS 0.25%

Last modified Jun 17, 2026

CVE-2025-6425 is a medium-severity vulnerability rated 4.3/10 on the CVSS scale. 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.. EPSS estimates a 0.25% chance of exploitation in the next 30 days.

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.

Metrics

CVSS 3.1

4.3/10

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

EPSS Probability

0.25%

16.1th percentile

Probability of exploitation in the next 30 days. Learn more

Weakness Enumeration

CWE-200

Affected Software

Vendor	Product	Versions
Mozilla	Firefox	< 115.25.0
Mozilla	Firefox	< 140.0
Mozilla	Firefox	>= 116.0, < 128.12.0

References

https://bugzilla.mozilla.org/show_bug.cgi?id=1717672Issue Tracking, Vendor Advisory
https://www.mozilla.org/security/advisories/mfsa2025-51/Vendor Advisory
https://www.mozilla.org/security/advisories/mfsa2025-52/Vendor Advisory
https://www.mozilla.org/security/advisories/mfsa2025-53/Vendor Advisory
https://www.mozilla.org/security/advisories/mfsa2025-54/Vendor Advisory
https://www.mozilla.org/security/advisories/mfsa2025-55/Vendor Advisory
https://lists.debian.org/debian-lts-announce/2025/06/msg00029.html
https://lists.debian.org/debian-lts-announce/2025/07/msg00002.html

Timeline

Published: Jun 24, 2025
Last Modified: Jun 17, 2026
Status: Modified

Frequently Asked Questions

What is CVE-2025-6425?

How severe is CVE-2025-6425?

CVE-2025-6425 has a CVSS score of 4.3/10 (MEDIUM severity). The EPSS model estimates a 0.25% probability of exploitation in the next 30 days.

How do I fix CVE-2025-6425?

Check the vendor references and advisories linked above for patched versions and mitigation guidance. You can also run a Strix scan to test if your systems are affected.

Are you affected by CVE-2025-6425?

Run a free Strix scan to check your systems for this vulnerability.

Scan your code now

Source: NVD / NIST