CVE-2023-4583: Mozilla Firefox

High severity, CVSS 7.5. EPSS: 0.7% chance of exploitation in the next 30 days.

When checking if the Browsing Context had been discarded in `HttpBaseChannel`, if the load group was not available then it was assumed to have already been discarded which was not always the case for private channels after the private session had ended. This vulnerability affects Firefox < 117, Firefox ESR < 115.2, and Thunderbird < 115.2.

Affected products

• Mozilla Firefox: before 117.0 (fixed in 117.0)
• Mozilla Firefox ESR: before 115.2 (fixed in 115.2)
• Mozilla Thunderbird: before 115.2 (fixed in 115.2)

Published 2023-09-11. Last modified 2026-06-17.