CVE-2026-77641: 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…

PriorityP340high8.2CVSS 3.1

AVNACLPRNUINSUCNILAH

EPSS

0.19%

9.1th percentile

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

2 ranges

Vendor	Product	Version range	Fixed in
torproject	tor	< 0.4.9.9	0.4.9.9
torproject	tor	>= 0.4.8.1-alpha < 0.4.9.9	0.4.9.9

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