CVE-2026-77641

EUVD-2026-63658
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.
ProviderTypeBase ScoreAtk. VectorAtk. ComplexityPriv. RequiredVector
mitreCNA
6.5 MEDIUM
NETWORK
HIGH
NONE
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:L/A:H
Base Score
CVSS 3.x
EPSS Score
Percentile: Unknown
Early Detection
Affected products identified ahead of NVD analysis through intelligence sources.
VendorProductVersionSource
torprojecttor
𝑥
< 0.4.9.9
CNA
Common Weakness Enumeration
References
https://gitlab.torproject.org/tpo/core/tor/-/raw/tor-0.4.9.9/ChangeLog