CVE-2026-35640

Received Received - Intake

Denial of Service via JSON Parsing in OpenClaw Webhooks

Publication date: 2026-04-09

Last updated on: 2026-04-15

Assigner: VulnCheck

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.

CVSS Scores

EPSS Scores

Probability:
Percentile:

Meta Information

Published

2026-04-09

Last Modified

2026-04-15

Generated

2026-07-06

AI Q&A

2026-04-10

EPSS Evaluated

2026-07-05

NVD

CVE-2026-35640

EUVD

EUVD-2026-21136

Affected Vendors & Products

Vendor	Product	Version / Range
openclaw	openclaw	to 2026.3.25 (exc)

Helpful Resources

Exploitability

CWE

KEV

CWE ID	Description
CWE-696	The product performs multiple related behaviors, but the behaviors are performed in the wrong order in ways that may produce resultant weaknesses.

Attack-Flow Graph

Executive Summary

This vulnerability exists in OpenClaw versions before 2026.3.25. The software parses JSON request bodies before validating webhook signatures, which allows unauthenticated attackers to send malicious webhook requests. These requests force the server to perform resource-intensive JSON parsing operations before rejecting the request based on an invalid signature.

As a result, attackers can trigger a denial of service (DoS) by exhausting server resources through these forced parsing operations.

Impact Analysis

The primary impact of this vulnerability is a denial of service condition. Remote attackers can exploit it to exhaust server resources by sending malicious webhook requests that trigger expensive JSON parsing before signature validation.

This can lead to degraded performance or unavailability of the affected OpenClaw service, potentially disrupting normal operations.

Hi! I’m here to help you understand CVE-2026-35640. Ask me anything about the vulnerability, its impact, or mitigation strategies.

0/70