Vulnerability · Published Aug 20, 2026 · Assigned by mitre
CVE-2026-77584
High 7.0
In plain English
A high-severity security flaw 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 0.2% (higher than 16% of all known vulnerabilities). Fixed versions are available - upgrade the affected package.
Official description
Tor before 0.4.9.10 did not reject a CONFLUX_LINK cell that arrives on a circuit which already has attached streams. A malicious client could send a RELAY_COMMAND_BEGIN before the CONFLUX_LINK on the same circuit, attaching an exit stream that would later end up orphan leaving a dangling circuit back-pointer and a use-after-free (UAF) when the circuit is freed. This is TROVE-2026-025.
Affected packages & fixed versions
| Ecosystem | Package | Fixed in | Advisory |
|---|---|---|---|
| Debian:12 | tor | 0.4.9.11-0+deb12u1 | DEBIAN-CVE-2026-77584 |
| Debian:13 | tor | 0.4.9.11-0+deb13u1 | DEBIAN-CVE-2026-77584 |
| Debian:14 | tor | 0.4.9.11-1 | DEBIAN-CVE-2026-77584 |
| Ubuntu:22.04:LTS | tor | no fix listed | UBUNTU-CVE-2026-77584 |
| Ubuntu:24.04:LTS | tor | no fix listed | UBUNTU-CVE-2026-77584 |
| Ubuntu:26.04:LTS | tor | no fix listed | UBUNTU-CVE-2026-77584 |
Affected products (as reported)
| Vendor | Product | Versions |
|---|---|---|
| torproject | Tor | 0.4.8.1-alpha – before 0.4.9.10 |
Weakness: CWE-821 · Vector: CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:H/A:L