Description
A security flaw has been discovered in Tor up to 0.4.7.16/0.4.8.17. Impacted is an unknown function of the component Onion Service Descriptor Handler. Performing manipulation results in resource consumption. The attack may be initiated remotely. The attack's complexity is rated as high. The exploitability is considered difficult. Upgrading to version 0.4.8.18 and 0.4.9.3-alpha is recommended to address this issue. It is recommended to upgrade the affected component.
Affected products
| Vendor | Product | Affected | Fixed |
|---|---|---|---|
| — | Tor | 0.4.7.0, 0.4.7.1, 0.4.7.2, 0.4.7.3, 0.4.7.4, 0.4.7.5, 0.4.7.6, 0.4.7.7, 0.4.7.8, 0.4.7.9, 0.4.7.10, 0.4.7.11, 0.4.7.12, 0.4.7.13, 0.4.7.14, 0.4.7.15, 0.4.7.16, 0.4.8.0, 0.4.8.1, 0.4.8.2, 0.4.8.3, 0.4.8.4, 0.4.8.5, 0.4.8.6, 0.4.8.7, 0.4.8.8, 0.4.8.9, 0.4.8.10, 0.4.8.11, 0.4.8.12, 0.4.8.13, 0.4.8.14,… | 0.4.8.18 |
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 | 0.4.8.21-1 | — |
| Debian 13 | tor | 0.4.9.6-0+deb13u1 | — |
| Debian 12 | tor | 0.4.9.6-0+deb12u1 | — |
Ubuntu
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Ubuntu 26.10 | tor | No fix yet | — |
| Ubuntu 26.04 LTS | tor | No fix yet | — |
| Ubuntu 25.10 | 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 | 0.4.8.18-1.1 | openSUSE-SU-2025:15571-1 |
Advisories 2
- openSUSE-SU-2025:15571-1 tor-0.4.8.18-1.1 on GA media SUSE / openSUSE Security Updates · Mar 23, 2026
- WID-SEC-2025-2089 Tor: Schwachstelle ermöglicht Denial of Service BSI CERT-Bund (WID) · Sep 28, 2025
References
- VDB-324814 | Tor Onion Service Descriptor resource consumption vdb-entry
- VDB-324814 | CTI Indicators (IOB, IOC, TTP) signature permissions-required
- Submit #640605 | Tor ≤ 0.4.8 Memory Management vulnerability third-party-advisory
- https://github.com/chunmianwang/Tordos related
- https://gitlab.torproject.org/tpo/core/tor/-/raw/release-0.4.8/ReleaseNotes release-notes
- https://forum.torproject.org/t/alpha-and-stable-release-0-4-8-18-and-0-4-9-3-alpha/20578 patch