CVE-2026-35640: OpenClaw < 2026.3.25 - Denial of Service via Unauthenticated Webhook Request Parsing

Severity: high (CVSS 7.5 v3.1)
Exploited in the wild: not listed in CISA KEV
EPSS: 0.4% probability of exploitation in the next 30 days
Public exploit or detection template: none known
Published: 2026-04-09 · updated 2026-06-17
Weakness: CWE-696

Description

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.

Affected products

OpenClaw: before 2026.3.25 — fixed in 2026.3.25

How to fix

Upgrade to a fixed version: OpenClaw 2026.3.25. Check the vendor advisory for mitigations.

References

https://github.com/openclaw/openclaw/commit/5e8cb22176e9235e224be0bc530699261eb60e53
https://github.com/openclaw/openclaw/security/advisories/GHSA-3h52-cx59-c456
https://www.vulncheck.com/advisories/openclaw-denial-of-service-via-unauthenticated-webhook-request-parsing

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