What’s Vulnerable › Vulnerabilities

CVE-2025-10531: Mitigation bypass in the Web Compatibility: Tooling component

• Severity: medium (CVSS 5.4 v3.1)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 0.3% probability of exploitation in the next 30 days
• Public exploit or detection template: none known
• Published: 2025-09-16 · updated 2026-10-18
• Weakness: CWE-288

Description

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

Affected products

• Mozilla Firefox: before 143.0 — fixed in 143.0
• Mozilla Thunderbird: before 143.0 — fixed in 143.0

How to fix

Upgrade to a fixed version: Mozilla Firefox 143.0; Mozilla Thunderbird 143.0. Check the vendor advisory for mitigations.

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/

Get alerted when CVE-2025-10531 or the next vulnerability affects your stack