Resource exhaustion in Tor
CVE-2025-4444
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.
Vulnerability class: DoS (Denial of Service)
Published · last modified .
CVSS v3 metric
CVSS v3 base score 3.7 (Low). Vector: CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:L.
EPSS exploit prediction
EPSS: 0.005 (38.7th percentile), scored .
Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 39th percentile — 38.7% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.
EPSS over last 30 days · oldest: 0.005 · newest: 0.005 · change: 0.000
Affected products
- Tor — versions 0.4.7.0, 0.4.7.1, 0.4.7.2
Weakness classification (CWE)
Public proof-of-concept exploits
References
- vuldb.com/ (vdb-entry)
- vuldb.com/ (signature, permissions-required)
- vuldb.com/ (third-party-advisory)
- github.com/chunmianwang/Tordos (related)
- gitlab.torproject.org/tpo/core/tor/-/raw/release-0.4.8/ReleaseNotes (release-notes)
- forum.torproject.org/t/alpha-and-stable-release-0-4-8-18-and-0-4-9-3-alpha/20578 (patch)
Frequently asked questions
- What is CVE-2025-4444?
- CVE-2025-4444 is a low-severity vulnerability in Tor, classified under Uncontrolled Resource Consumption. CVSS score: 3.7/10. Published 2025-09-18.
- How severe is CVE-2025-4444?
- Low severity. CVSS v3 base score is 3.7 out of 10.
- Is CVE-2025-4444 known to be exploited?
- 1 public proof-of-concept repositories are indexed. Not currently listed in the CISA KEV catalog.