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CVE-2026-77638

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.

在 Tor 版本低于 0.4.9.11 的情况下，存在一个竞态条件漏洞。在特定条件下，中间人攻击者可以利用该漏洞冒充客户端试图访问的洋葱服务，从而对通信进行中间人攻击（MITM）。

CVSS 8.9 · High EPSS 0.17% · P7

Possible ATT&CK Techniques 1 AI

T1557 · Adversary-in-the-Middle

Affected Version Matrix 1

VendorProduct Version RangeStatus
torproject Tor 0.3.5.3-alpha< 0.4.9.11 affected
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I. Basic Information for CVE-2026-77638

Vulnerability Information
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Vulnerability Title
N/A
Source: CVE Program / CVE List V5
Vulnerability Description
Tor before 0.4.9.11 is prone to a race condition where in just the right circumstances a rendezvous point could man-in-the-middle (impersonate) the onion service that the client was trying to reach.
Source: CVE Program / CVE List V5
CVSS Information
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:C/C:H/I:H/A:L
Source: CVE Program / CVE List V5
Vulnerability Type
使用共享资源的并发执行不恰当同步问题(竞争条件)
Source: CVE Program / CVE List V5

Affected Products

Vendor Product Affected Versions CPE Subscribe
torproject Tor 0.3.5.3-alpha ~ 0.4.9.11 -

II. Public POCs for CVE-2026-77638

# POC Description Source Link Shenlong Link
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III. Intelligence Information for CVE-2026-77638

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Patches & Fixes for CVE-2026-77638 (1)

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

CVE-2026-77642 7.5 HIGH Tor <0.4.9.9共识解析越界写入漏洞
CVE-2026-77584 7.0 HIGH Tor <0.4.9.10 释放后使用漏洞
CVE-2026-77641 6.5 MEDIUM Tor 0.4.9.9前版本释放后空指针写入漏洞
CVE-2026-77587 5.9 MEDIUM Tor 0.4.9.11前存在释放后使用漏洞
CVE-2026-77639 5.3 MEDIUM Tor <0.4.9.9 压缩炸弹绕过漏洞
CVE-2026-77640 3.7 LOW Tor <0.4.9.9 zlib截断流无限循环漏洞

IV. Related Vulnerabilities

Same product: Tor
Same vendor: torproject
Same weakness: CWE-362

V. Comments for CVE-2026-77638

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