CVE-2026-77641: Torproject Tor

High severity, CVSS 8.2. EPSS: 0.4% chance of exploitation in the next 30 days.

tor before 0.4.9.9 was prone to a NULL write after free when sending a CONFLUX_SWITCH cell fails. The return value of relay_send_command_from_edge() was ignored, so a send failure (which calls circuit_mark_for_close() and removes the leg via cfx_del_leg()) would go undetected, causing the caller to write to the now-freed current leg and resulting in a crash. This is TROVE-2026-017.

Affected products

Published 2026-08-20. Last modified 2026-09-08.