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 products
| Vendor | Product | Affected | Fixed |
|---|---|---|---|
| torproject | Tor | 0.4.8.1-alpha – < 0.4.9.10 | 0.4.9.10 |
Fixed in Linux distributions
Distributions backport fixes, so the version that fixes this vulnerability differs per release — upgrade to at least the version shown. From the distributions' security trackers and advisories.
Debian
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Debian 14 | tor | 0.4.9.11-1 | — |
| Debian 13 | tor | 0.4.9.11-0+deb13u1 | — |
| Debian 12 | tor | 0.4.9.11-0+deb12u1 | — |
Ubuntu
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Ubuntu 26.04 LTS | tor | No fix yet | — |
| Ubuntu 24.04 LTS | tor | No fix yet | — |
| Ubuntu 22.04 LTS | tor | No fix yet | — |
Show 4 more (older releases, extended support, other products)Fewer releases
| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Ubuntu Pro 20.04 LTS | tor | No fix yet | — |
| Ubuntu Pro 18.04 LTS | tor | No fix yet | — |
| Ubuntu Pro 16.04 LTS | tor | No fix yet | — |
| Ubuntu Pro 14.04 LTS | tor | No fix yet | — |
openSUSE
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| openSUSE Tumbleweed | tor | 0.4.9.11-1.1 | openSUSE-SU-2026:11590-1 |
| openSUSE Leap 16.0 | tor | 0.4.9.11-bp160.1.1 | openSUSE-SU-2026:21660-1 |
Advisories 3
- WID-SEC-2026-2959 Tor: Mehrere Schwachstellen BSI CERT-Bund (WID) · Aug 30, 2026
- openSUSE-SU-2026:21660-1 Security update for tor SUSE / openSUSE Security Updates · Aug 27, 2026
- openSUSE-SU-2026:11590-1 tor-0.4.9.11-1.1 on GA media SUSE / openSUSE Security Updates · Aug 26, 2026