CVE-2025-10531

Mitigation bypass in the Web Compatibility: Tooling component. This vulnerability was fixed in Firefox 143 and Thunderbird 143.

CVSS 3.1

5.4CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:L/I:L/A:N

EPSS

0.3% chance of exploitation in the next 30 days; higher than 19% of CVEs (scores of 2026-10-25)

CWE

CWE-288

Published

2025-09-16

Modified

2026-10-18

Record from

the NVD, synced 2026-10-19

Affected

• mozilla:firefox
• mozilla:thunderbird

References

• https://bugzilla.mozilla.org/show_bug.cgi?id=1978453
• https://www.mozilla.org/security/advisories/mfsa2025-73/
• https://www.mozilla.org/security/advisories/mfsa2025-77/

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