CVE-2024-7531: Mozilla Firefox

Medium severity, CVSS 6.5. EPSS: 0.4% chance of exploitation in the next 30 days.

Calling `PK11_Encrypt()` in NSS using CKM_CHACHA20 and the same buffer for input and output can result in plaintext on an Intel Sandy Bridge processor. In Firefox this only affects the QUIC header protection feature when the connection is using the ChaCha20-Poly1305 cipher suite. The most likely outcome is connection failure, but if the connection persists despite the high packet loss it could be possible for a network observer to identify packets as coming from the same source despite a network path change. This vulnerability affects Firefox < 129, Firefox ESR < 115.14, and Firefox ESR < 128.1.

Affected products

• Mozilla Firefox: before 129.0 (fixed in 129.0)
• Mozilla Firefox ESR: before 115.14.0 (fixed in 115.14.0); version 128.0 only

Published 2024-08-06. Last modified 2026-06-17.