CVE-2025-3032: Leaking file descriptors from the fork server

Severity: high (CVSS 7.4 v3.1)
Exploited in the wild: not listed in CISA KEV
EPSS: 0.4% probability of exploitation in the next 30 days
Public exploit or detection template: none known
Published: 2025-04-01 · updated 2026-09-30
Weakness: CWE-403

Description

Leaking of file descriptors from the fork server to web content processes could allow for privilege escalation attacks. This vulnerability was fixed in Firefox 137 and Thunderbird 137.

Affected products

Mozilla Firefox: before 137.0 — fixed in 137.0
Mozilla Thunderbird: before 137.0 — fixed in 137.0

How to fix

Upgrade to a fixed version: Mozilla Firefox 137.0; Mozilla Thunderbird 137.0. Check the vendor advisory for mitigations.

References

https://bugzilla.mozilla.org/show_bug.cgi?id=1949987
https://www.mozilla.org/security/advisories/mfsa2025-20/
https://www.mozilla.org/security/advisories/mfsa2025-23/

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