CVE-2023-6865: Debian Linux

Medium severity, CVSS 6.5. EPSS: 0.9% chance of exploitation in the next 30 days.

`EncryptingOutputStream` was susceptible to exposing uninitialized data. This issue could only be abused in order to write data to a local disk which may have implications for private browsing mode. This vulnerability affects Firefox ESR < 115.6 and Firefox < 121.

Affected products

• Debian Debian Linux: version 10.0 only; version 11.0 only; version 12.0 only
• Mozilla Firefox: before 121.0 (fixed in 121.0)
• Mozilla Firefox ESR: before 115.6 (fixed in 115.6)

Published 2023-12-19. Last modified 2026-06-17.