CVE-2026-53837: OpenClaw < 2026.5.6 - Missing Channel Type Validation in Mattermost Event Handlers

Severity: medium (CVSS 5.3 v3.1)
Exploited in the wild: not listed in CISA KEV
EPSS: 0.2% probability of exploitation in the next 30 days
Public exploit or detection template: none known
Published: 2026-06-12 · updated 2026-07-23
Weakness: CWE-636

Description

OpenClaw before 2026.5.6 contains an improper access control vulnerability in Mattermost event handlers that fails to validate channel type metadata. Attackers can bypass intended DM policy decisions by sending crafted Mattermost events missing channel type information to process restricted content.

Affected products

OpenClaw: before 2026.5.6 — fixed in 2026.5.6

How to fix

Upgrade to a fixed version: OpenClaw 2026.5.6. Check the vendor advisory for mitigations.

References

https://github.com/openclaw/openclaw/security/advisories/GHSA-gp79-m99v-gjmh
https://www.vulncheck.com/advisories/openclaw-missing-channel-type-validation-in-mattermost-event-handlers

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