# CVE-2026-77641

## Summary

- **CVE ID:** CVE-2026-77641
- **Severity:** MEDIUM
- **CVSS Score:** 6.5 (CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:L/A:H)
- **CWE:** CWE-252
- **Published:** Aug 20, 2026
- **Last Modified:** Aug 27, 2026

## 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.

## Affected Products

- torproject — Tor (0.4.8.1-alpha)

## References

- [CNA](https://gitlab.torproject.org/tpo/core/tor/-/raw/tor-0.4.9.9/ChangeLog)

## Exploitation Prediction (EPSS)

- **EPSS Score:** 0.19%
- **EPSS Percentile:** 9.1

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_Exported from OnDuty AI Vulnerability Intelligence on 2026-09-10._