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CVE-2026-77641

Quick assessment

Affected
torproject Tor
Exploitation
No confirmed in-the-wild exploitation; assess based on exposure
Recommended action
Check the vendor advisory and references for a fixed version. If immediate upgrade is impossible, restrict exposure and increase monitoring.

torproject Tor是torproject组织开源的一款匿名通信软件。 torproject Tor 0.4.9.9之前版本存在异常处理不当漏洞，该漏洞源于发送CONFLUX_SWITCH cell失败时忽略relay_send_command_from_edge()返回值，导致释放后空指针写入，可能导致崩溃。

CVSS 6.5 · Medium EPSS 0.35% · P27

Possible ATT&CK Techniques 1 AI

T1499 · Endpoint Denial of Service

Affected Version Matrix 1

VendorProduct Version RangeStatus
torproject Tor 0.4.8.1-alpha< 0.4.9.9 affected
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I. Basic Information for CVE-2026-77641

Vulnerability Information
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Vulnerability Title
N/A
Source: CVE Program / CVE List V5
Vulnerability 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.
Source: CVE Program / CVE List V5
CVSS Information
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:L/A:H
Source: CVE Program / CVE List V5
Vulnerability Type
未加检查的返回值
Source: CVE Program / CVE List V5
Vulnerability Title
torproject Tor 异常处理不当漏洞
Source: CNNVD (China National Vulnerability Database)
Vulnerability Description
torproject Tor是torproject组织开源的一款匿名通信软件。 torproject Tor 0.4.9.9之前版本存在异常处理不当漏洞，该漏洞源于发送CONFLUX_SWITCH cell失败时忽略relay_send_command_from_edge()返回值，导致释放后空指针写入，可能导致崩溃。
Source: CNNVD (China National Vulnerability Database)
CVSS Information
N/A
Source: CNNVD (China National Vulnerability Database)
Vulnerability Type
N/A
Source: CNNVD (China National Vulnerability Database)

Affected Products

Vendor Product Affected Versions CPE Subscribe
torproject Tor 0.4.8.1-alpha ~ 0.4.9.9 -

II. Public POCs for CVE-2026-77641

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III. Intelligence Information for CVE-2026-77641

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Other References for CVE-2026-77641 (1)

Same Patch Batch · torproject · 2026-08-20 · 7 CVEs total

CVE-2026-77638 8.9 HIGH torproject Tor 竞争条件问题漏洞
CVE-2026-77642 7.5 HIGH torproject Tor 缓冲区错误漏洞
CVE-2026-77584 7.0 HIGH torproject Tor 竞争条件问题漏洞
CVE-2026-77587 5.9 MEDIUM torproject Tor 资源管理错误漏洞
CVE-2026-77639 5.3 MEDIUM torproject Tor 授权问题漏洞
CVE-2026-77640 3.7 LOW torproject Tor 输入验证错误漏洞

IV. Related Vulnerabilities

Same product: Tor
Same vendor: torproject
Same weakness: CWE-252

V. Comments for CVE-2026-77641

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