Vulnerability in Openclaw
CVE-2026-35640
OpenClaw before 2026.3.25 parses JSON request bodies before validating webhook signatures, allowing unauthenticated attackers to force resource-intensive parsing operations. Remote attackers can send malicious webhook requests to trigger denial of service by exhausting server resources through forced JSON parsing before signature rejection.
Published · last modified .
CVSS v3 metric
CVSS v3 base score 5.3 (Medium). Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L.
EPSS exploit prediction
EPSS: 0.008 (55.5th percentile), scored .
Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 56th percentile — 55.5% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.
EPSS over last 30 days · oldest: 0.004 · newest: 0.008 · change: +0.004
Affected products
- Openclaw — versions 0, 2026.3.25
Weakness classification (CWE)
References
- github.com/openclaw/openclaw/security/advisories/GHSA-3h52-cx59-c456 (vendor-advisory, Vendor Advisory, third-party-advisory)
- github.com/openclaw/openclaw/commit/5e8cb22176e9235e224be0bc530699261eb60e53 (Patch, patch)
- www.vulncheck.com/advisories/openclaw-denial-of-service-via-unauthenticated-web… (Third Party Advisory, third-party-advisory)
Frequently asked questions
- What is CVE-2026-35640?
- CVE-2026-35640 is a medium-severity vulnerability in Openclaw, classified under CWE-696. CVSS score: 5.3/10. Published 2026-04-09.
- How severe is CVE-2026-35640?
- Medium severity. CVSS v3 base score is 5.3 out of 10.