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 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.

CVSS v3 6.5 MEDIUM

6.5^/10

CVSS v3 : MEDIUM

Vector :

Exploitability : 2.2 / Impact : 4.2

Attack Vector NETWORK

Attack Complexity HIGH

Privileges Required NONE

User Interaction NONE

Confidentiality Impact NONE

Integrity Impact LOW

Availability Impact HIGH

Scope UNCHANGED

References

Link	Resource
https://gitlab.torproject.org/tpo/core/tor/-/raw/tor-0.4.9.9/ChangeLog	Release Notes Vendor Advisory

Configurations

Configuration 1 (hide)

cpe:2.3:a:torproject:tor:*:*:*:*:*:*:*:*

History

No history.

Information

Published : 2026-08-20 21:17

Updated : 2026-09-08 18:23

NVD link : CVE-2026-77641

Mitre link : CVE-2026-77641

CVE.ORG link : CVE-2026-77641

JSON object : View

Products Affected

torproject

tor

CWE

CWE-252

Unchecked Return Value

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