CVE-2025-5262

Severity: high (CVSS 7.5 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: 2025-05-27 · updated 2026-06-17
Weakness: CWE-415

Description

A double-free could have occurred in `vpx_codec_enc_init_multi` after a failed allocation when initializing the encoder for WebRTC. This could have caused memory corruption and a potentially exploitable crash. This vulnerability affects Thunderbird < 139 and Thunderbird < 128.11.

Affected products

Mozilla Thunderbird: before 128.11.0; before 139.0 — fixed in 128.11.0, 139.0

How to fix

Upgrade to a fixed version: Mozilla Thunderbird 128.11.0, 139.0. Check the vendor advisory for mitigations.

References

https://bugzilla.mozilla.org/show_bug.cgi?id=1962421
https://www.mozilla.org/security/advisories/mfsa2025-45/
https://www.mozilla.org/security/advisories/mfsa2025-46/

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