CVE-2026-77638

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.

9.0 CRITICALEPSS 0.29%Not in KEVNVD: Analyzed

Last updated: 2026-10-18 20:10 UTC

OverviewCVSS details

9.0CRITICALCVSS 3.1

Score source: NVD
NVD status: Analyzed
Published: Aug 20, 2026
Assigner: mitre

Affected

Tor (torproject)

Versions: 0.3.5.3-alpha before 0.4.9.11
Fixed in: 0.4.9.11

Exploitation

Public exploit: None listed
CISA KEV: Not listed
KEV due date: —
SSVC: Exploitation none · Automatable no · Impact total

EPSS · FIRST, scored Nov 7

0.29%chance of exploitation in 30 days

Higher than 22.68% of CVEs

CVSS 3.1 · NVD

9.0Critical

CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:C/C:H/I:H/A:H

Attack vector: Network
Attack complexity: High
Privileges required: None
User interaction: None
Scope: Changed
Confidentiality impact: High
Integrity impact: High
Availability impact: High

CVSS 3.1 · mitre (CNA)

8.9High

CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:C/C:H/I:H/A:L

Attack vector: Network
Attack complexity: High
Privileges required: None
User interaction: None
Scope: Changed
Confidentiality impact: High
Integrity impact: High
Availability impact: Low

NVD status: Analyzed

Overview Affected Products References

NVD CVE.org

Overview

Severity

Score	Severity	Version	Vector String
9.0	CRITICAL	3.1NVD	CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:C/C:H/I:H/A:H
8.9	HIGH	3.1mitre (CNA)	CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:C/C:H/I:H/A:L

Details

CVE ID: CVE-2026-77638
Status: Analyzed
Assigner (CNA): mitre
Published: Aug 20, 2026
Last modified: 2026-10-18 20:10 UTC
Weaknesses: CWE-362 · Concurrent Execution using Shared Resource with Improper Synchronization ('Race Condition')

Sources

Refreshed hourly from the sources above. Last fetched 2026-11-08 10:45 UTC.