Is there a patch available for CVE-2026-53837?

Yes, a patch is available for CVE-2026-53837. Update the affected software to the latest version immediately.

OpenClaw CVE-2026-53837

Q: What is the CVSS score of CVE-2026-53837?

CVE-2026-53837 has a CVSS 4.0 base score of 6.3 (Medium). CVSS vector: CVSS:4.0/AV:N/AC:H/AT:P/PR:N/UI:N/VC:N/VI:L/VA:N/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X. EPSS exploitation probability: 0.0%.

EUVD-2026-36625 MEDIUM

Not Failing Securely ('Failing Open') (CWE-636)

2026-06-12 VulnCheck

GHSA-chqm-wxm2-w73w

Authentication Bypass Mattermost Openclaw

6.3

CVSS 4.0 · Vendor: VulnCheck

Severity by source

Vendor (VulnCheck) PRIMARY

6.3 MEDIUM

CVSS:4.0/AV:N/AC:H/AT:P/PR:N/UI:N/VC:N/VI:L/VA:N/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X

vuln.today AI

3.7 LOW

Network-reachable unauthenticated flaw requiring crafted event delivery (AC:H); impact is limited to low integrity bypass with no confidentiality or availability effect.

3.1 AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:L/A:N

4.0 AV:N/AC:H/AT:P/PR:N/UI:N/VC:N/VI:L/VA:N/SC:N/SI:N/SA:N

Primary rating from Vendor (VulnCheck).

CVSS VectorVendor: VulnCheck

CVSS:4.0/AV:N/AC:H/AT:P/PR:N/UI:N/VC:N/VI:L/VA:N/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X

Attack Vector

Network

Attack Complexity

High

Privileges Required

None

User Interaction

None

Scope

Lifecycle Timeline

Patch available

Jun 13, 2026 - 02:00 EUVD

Analysis Generated

Jun 12, 2026 - 22:45 vuln.today

Blast Radius

ecosystem impact

† from your stack dependencies † transitive graph · vuln.today resolves 4-path depth

1 npm packages depend on openclaw (1 direct, 0 indirect)

Ecosystem-wide dependent count for version 2026.5.6.

DescriptionCVE.org

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.

AnalysisAI

Improper access control in OpenClaw's Mattermost event handler integration allows remote unauthenticated attackers to bypass direct message (DM) policy enforcement by submitting crafted Mattermost events that deliberately omit channel type metadata. All OpenClaw versions prior to 2026.5.6 are affected. No public exploit or active exploitation has been identified at time of analysis, but the network-accessible and unauthenticated nature of the flaw (PR:N per CVSS 4.0) makes it actionable for deployments that rely on DM policies as a meaningful access control boundary.

Technical ContextAI

OpenClaw (CPE: cpe:2.3:a:openclaw:openclaw:*:*:*:*:*:*:*:*) integrates with Mattermost's event-driven messaging platform, processing incoming Mattermost events including those governing direct message channel access. The root cause is CWE-636 ('Not Failing Securely - Fail Open'): when an event arrives with the channel_type metadata field absent, the handler does not reject or quarantine the malformed event. Instead, it processes the event without applying the intended DM policy logic, defaulting to permissive behavior. This is a classic fail-open security defect where missing input is treated as a permitted state rather than an error requiring denial. The CVSS 4.0 AT:P metric confirms that specific attack prerequisites - namely, the ability to send Mattermost events with crafted missing fields - must be in place for exploitation.

RemediationAI

The primary fix is to upgrade OpenClaw to version 2026.5.6 or later, which resolves the missing channel_type validation in the Mattermost event handler. The vendor advisory at https://github.com/openclaw/openclaw/security/advisories/GHSA-gp79-m99v-gjmh should be consulted for upgrade instructions. If immediate patching is not feasible, restrict network-level access to OpenClaw's Mattermost event handler endpoints so that only traffic originating from the trusted Mattermost server is accepted - this reduces the attack surface by preventing arbitrary external parties from delivering crafted events, though it does not eliminate risk from compromised Mattermost integration tokens. Additionally, enabling application-level logging for malformed or incomplete Mattermost events (those missing channel_type fields) can serve as a detection control to identify exploitation attempts while a patch is being deployed.