CVE-2026-77641
Medium
Description
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.
SeverityMedium
CVSS6.5
Exploit probability—
ProductTor
PublishedAug 20, 2026
First seenAug 20, 2026
Weakness typeCWE-252CWE-252
How to fix
Update
- torproject tor0.4.9.9 or later
Affected products
| Product | Affected versions | Fixed in |
|---|---|---|
| torproject tor | v < 0.4.9.9 | 0.4.9.9 |
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