Vulnerability · Published Aug 20, 2026 · Assigned by mitre
CVE-2026-77638
High 8.9
In plain English
A high-severity race condition in Tor from torproject. There are no confirmed reports of exploitation so far. The chance it is exploited in the next 30 days is estimated at 0.3% (higher than 23% of all known vulnerabilities). Fixed versions are available - upgrade the affected package.
Severity (CVSS 3.1)8.9High
Exploit odds (30 days)0.3%top 77.3% of all CVEs
Exploited in the wildNo reportsCISA SSVC: none
Attack toolingNoneno public tooling known
Official 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.
Affected packages & fixed versions
| Ecosystem | Package | Fixed in | Advisory |
|---|---|---|---|
| Debian:12 | tor | 0.4.9.11-0+deb12u1 | DEBIAN-CVE-2026-77638 |
| Debian:13 | tor | 0.4.9.11-0+deb13u1 | DEBIAN-CVE-2026-77638 |
| Debian:14 | tor | 0.4.9.11-1 | DEBIAN-CVE-2026-77638 |
| Ubuntu:22.04:LTS | tor | no fix listed | UBUNTU-CVE-2026-77638 |
| Ubuntu:24.04:LTS | tor | no fix listed | UBUNTU-CVE-2026-77638 |
| Ubuntu:26.04:LTS | tor | no fix listed | UBUNTU-CVE-2026-77638 |
Affected products (as reported)
| Vendor | Product | Versions |
|---|---|---|
| torproject | Tor | 0.3.5.3-alpha – before 0.4.9.11 |
Weakness: CWE-362 · Vector: CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:C/C:H/I:H/A:L