Description
Tor before 0.2.4.26 and 0.2.5.x before 0.2.5.11 does not properly handle pending-connection resolve states during periods of high DNS load, which allows remote attackers to cause a denial of service (assertion failure and daemon exit) via crafted packets.
Affected products
| Vendor | Product | Affected | Fixed |
|---|---|---|---|
| The Tor Project | Tor | before 0.2.4.26, 0.2.5.x before 0.2.5.11 | — |
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 | 0.2.5.11-1 | — |
| Debian 13 | tor | 0.2.5.11-1 | — |
| Debian 12 | tor | 0.2.5.11-1 | — |
| Debian 7 | tor | 0.2.4.26-1 | DSA-3203-1 |
| Debian 6.0 | tor | 0.2.4.26-1~deb6u1 | DLA-178-1 |
Ubuntu
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Ubuntu 14.04 LTS | tor | 0.2.4.27-1build0.14.04.1 | — |
openSUSE
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| openSUSE Tumbleweed | tor | 0.2.8.11-1.1 | openSUSE-SU-2024:10423-1 |
Advisories 3
- DLA-178-1 tor - security update Debian Security (DSA / DLA) · Mar 9, 2026
- DSA-3203-1 tor - security update Debian Security (DSA / DLA) · Mar 9, 2026
- openSUSE-SU-2024:10423-1 tor-0.2.8.11-1.1 on GA media SUSE / openSUSE Security Updates · Feb 4, 2026