What’s Vulnerable › Vulnerabilities

CVE-2025-1934: Unexpected GC during RegExp bailout processing

• Severity: medium (CVSS 6.5 v3.1)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 0.5% probability of exploitation in the next 30 days
• Public exploit or detection template: none known
• Published: 2025-03-04 · updated 2026-10-05

Description

It was possible to interrupt the processing of a RegExp bailout and run additional JavaScript, potentially triggering garbage collection when the engine was not expecting it. This vulnerability was fixed in Firefox 136, Firefox ESR 128.8, Thunderbird 136, and Thunderbird 128.8.

Affected products

• Mozilla Firefox: before 128.8.0; before 136.0 — fixed in 128.8.0, 136.0
• Mozilla Thunderbird: before 128.8.0; from 129.0 before 136.0 — fixed in 128.8.0, 136.0

How to fix

Upgrade to a fixed version: Mozilla Firefox 128.8.0, 136.0; Mozilla Thunderbird 128.8.0, 136.0. Check the vendor advisory for mitigations.

References

• https://bugzilla.mozilla.org/show_bug.cgi?id=1942881
• https://www.mozilla.org/security/advisories/mfsa2025-14/
• https://www.mozilla.org/security/advisories/mfsa2025-16/
• https://www.mozilla.org/security/advisories/mfsa2025-17/
• https://www.mozilla.org/security/advisories/mfsa2025-18/
• https://lists.debian.org/debian-lts-announce/2025/03/msg00006.html

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