Description
Tor before 0.4.5.7 allows a remote participant in the Tor directory protocol to exhaust CPU resources on a target, aka TROVE-2021-001.
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 | 0.4.5.7-1 | — |
| Debian 13 | tor | 0.4.5.7-1 | — |
| Debian 12 | tor | 0.4.5.7-1 | — |
| Debian 10 | tor | 0.3.5.14-1 | DSA-4871-1 |
Ubuntu
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Ubuntu Pro 20.04 LTS | tor | 0.4.2.7-1ubuntu0.1~esm1 | USN-5036-1 |
| Ubuntu Pro 18.04 LTS | tor | 0.3.2.10-1ubuntu0.2~esm2 | USN-5036-1 |
| Ubuntu Pro 16.04 LTS | tor | 0.2.9.14-1ubuntu1~16.04.3+esm1 | USN-5036-1 |
Show 1 more (older releases, extended support, other products)Fewer releases
| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Ubuntu Pro 14.04 LTS | tor | 0.2.4.27-1ubuntu0.1+esm2 | USN-5036-1 |
SUSE
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| SUSE Package Hub 15 SP2 | tor | 0.4.5.7-bp152.2.9.1 | openSUSE-SU-2021:0474-1 |
openSUSE
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| openSUSE Tumbleweed | tor | 0.4.6.7-2.2 | openSUSE-SU-2024:11469-1 |
| openSUSE Leap 15.2 | tor | 0.4.5.7-lp152.2.9.1 | openSUSE-SU-2021:0461-1 |
Alpine
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Alpine v3.24 | tor | 0.4.5.7-r0 | — |
| Alpine v3.23 | tor | 0.4.5.7-r0 | — |
| Alpine v3.22 | tor | 0.4.5.7-r0 | — |
| Alpine v3.21 | tor | 0.4.5.7-r0 | — |
| Alpine v3.20 | tor | 0.4.5.7-r0 | — |
Show 10 more (older releases, extended support, other products)Fewer releases
| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Alpine v3.19 | tor | 0.4.5.7-r0 | — |
| Alpine v3.18 | tor | 0.4.5.7-r0 | — |
| Alpine v3.17 | tor | 0.4.5.7-r0 | — |
| Alpine v3.16 | tor | 0.4.5.7-r0 | — |
| Alpine v3.15 | tor | 0.4.5.7-r0 | — |
| Alpine v3.14 | tor | 0.4.5.7-r0 | — |
| Alpine v3.13 | tor | 0.4.4.8-r0 | — |
| Alpine v3.12 | tor | 0.4.4.9-r0 | — |
| Alpine v3.11 | tor | 0.4.4.9-r0 | — |
| Alpine v3.10 | tor | 0.3.5.14-r0 | — |
Advisories 5
- USN-5036-1 tor vulnerabilities Ubuntu Security Notices (USN) · Jun 29, 2026
- DSA-4871-1 tor - security update Debian Security (DSA / DLA) · Mar 9, 2026
- openSUSE-SU-2021:0474-1 Security update for tor SUSE / openSUSE Security Updates · Feb 4, 2026
- openSUSE-SU-2024:11469-1 tor-0.4.6.7-2.2 on GA media SUSE / openSUSE Security Updates · Feb 4, 2026
- openSUSE-SU-2021:0461-1 Security update for tor SUSE / openSUSE Security Updates · Feb 4, 2026
References
- https://gitlab.torproject.org/tpo/core/tor/-/issues/40304
- https://blog.torproject.org/node/2009
- FEDORA-2021-e68317166d vendor-advisory
- GLSA-202107-25 vendor-advisory