CVE-2026-53837: OpenClaw Mattermost Handlers Could Fall Open Vulnerability

MODERATE
Advisory Identifier: GHSA-gp79-m99v-gjmh
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CVSS 3.7
CWE-636
Published
Advisory Summary

CVE-2026-53837 is a MODERATE (CVSS 3.7) mattermost handlers could fall open vulnerability (CWE-636: Not Failing Securely ('Failing Open')) affecting OpenClaw libraries in the npm ecosystem. The issue involves mattermost handlers could fall open when channel type was missing. Remediation is available by upgrading affected packages to version 2026.5.6.

CVE-2026-53837 at a Glance

CVE Identifier CVE-2026-53837
GHSA Identifier GHSA-gp79-m99v-gjmh
Severity MODERATE
CVSS v3.1 Base Score 3.7
CWE Classification CWE-636: Not Failing Securely ('Failing Open')
Affected Product OpenClaw
Package Ecosystem npm
Published Date
Last Updated

Security Impact

CVSS: 3.7

The security impact metrics below are parsed directly from the CVSS v3.1 vector string (CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:L/A:N).

Attack Vector Network (AV:N)
Attack Complexity High (AC:H)
Privileges Required None (PR:N)
User Interaction None (UI:N)
Scope Unchanged (S:U)
Confidentiality None (C:N)
Integrity Low (I:L)
Availability None (A:N)

How to Fix CVE-2026-53837

To remediate this vulnerability, upgrade all affected OpenClaw dependencies to a patched release. Both direct and transitive dependencies should be checked, as frameworks or security libraries may pull in vulnerable versions transitively.

openclaw fixed: 2026.5.6 
npm install openclaw@2026.5.6
Verify Direct and Transitive Dependencies

Run the following command in your project directory to verify that all resolved dependencies use the patched release: 

npm ls openclaw

How to Check if You Are Affected

To determine whether your Node.js application is affected by CVE-2026-53837, inspect your project dependencies using npm:

npm ls openclaw

Analyze the terminal output to locate any version of OpenClaw in your dependency tree. If any resolved version matches the vulnerable ranges listed in the table below (for example, versions earlier than 2026.5.6), your application is affected.

Note: The npm ls openclaw command inspects dependencies declared in your package.json and lockfile; it does not perform automated runtime dynamic scanning.

Technical Details

Vulnerability Mechanism & Technical Analysis

This vulnerability is classified under CWE-636: Not Failing Securely ('Failing Open'), where when the product encounters an error condition or failure, its design requires it to fall back to a state that is less secure than other options that are available, such as selecting the weakest encryption algorithm or using the most permissive access control restrictions. In OpenClaw, software state validation or input boundaries are circumvented during processing. Review the official source advisory statement below for specific affected components, classes, and reproduction details.

Source Advisory Statement

### Summary Mattermost handlers could fall open when channel type was missing. In affected versions, a Mattermost event missing channel type metadata could continue without applying the intended DM policy decision. This advisory is scoped to the named feature and configuration. It does not change OpenClaw's trusted-operator model: authenticated Gateway operators, installed plugins, and intentional local execution surfaces remain trusted unless a separate policy, approval, allowlist, sandbox, or auth boundary is crossed. ### Impact When the affected feature is enabled and reachable, this could process a Mattermost event that should have been gated by channel policy. Practical impact depends on the operator's configuration and whether lower-trust input can reach that path. ### Patched Versions The first stable patched version is `2026.5.6`. ### Mitigations keep Mattermost bot access restricted and review channel metadata errors until patched. As general hardening, keep channel and tool allowlists narrow, avoid sharing one Gateway between mutually untrusted users, and disable the affected feature when it is not needed.

CVE-2026-53837 Affected OpenClaw Versions

1 component(s)
Fixed Versions:
2026.5.6
Product / Package Ecosystem Affected Versions Fixed Version
openclaw
npm/openclaw
npm
< 2026.5.6
2026.5.6

References

GitHub Advisory / Wiki ADVISORY
https://github.com/openclaw/openclaw/security/advisories/GHSA-gp79-m99v-gjmh
NVD — CVE-2026-53837 NVD
https://nvd.nist.gov/vuln/detail/CVE-2026-53837
OpenClaw Source Repository REPOSITORY
https://github.com/openclaw/openclaw
www.vulncheck.com/advisories/openclaw... WEB
https://www.vulncheck.com/advisories/openclaw-missing-channel-type-validation-in-mattermost-event-handlers

Frequently Asked Questions

What is CVE-2026-53837?
CVE-2026-53837 is a security vulnerability in OpenClaw involving Mattermost handlers could fall open when channel type was missing under CWE-636: Not Failing Securely ('Failing Open').
Which OpenClaw versions are affected?
Affected versions include releases prior to 2026.5.6 across affected packages: openclaw.
What version fixes CVE-2026-53837?
Upgrading to 2026.5.6 (or the latest patched release for your respective branch) resolves the vulnerability.
Is openclaw affected?
Yes, openclaw is affected in releases prior to 2026.5.6. Upgrade your dependency to 2026.5.6 or later.
What is the CVSS score of CVE-2026-53837?
CVE-2026-53837 has a CVSS v3.1 base score of 3.7 (MODERATE) with vector string CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:L/A:N.
What CWE is associated with CVE-2026-53837?
CVE-2026-53837 is classified under CWE-636: Not Failing Securely ('Failing Open') (When the product encounters an error condition or failure, its design requires it to fall back to a state that is less secure than other options that are available, such as selecting the weakest encryption algorithm or using the most permissive access control restrictions.).
How can I check npm dependencies for CVE-2026-53837?
Run the dependency tree command: 'npm ls openclaw'. This command lists direct and transitive dependencies in your build configuration so you can verify if a vulnerable version is resolved.
Machine-readable OSV JSON OSV v1.5 Schema
Normalized schema output
View Raw JSON 
{
  "schema_version" : "1.4.0",
  "id" : "GHSA-gp79-m99v-gjmh",
  "modified" : "2026-08-28T15:53:28Z",
  "published" : "2026-07-02T16:45:14Z",
  "aliases" : [ "CVE-2026-53837" ],
  "summary" : "OpenClaw: Mattermost handlers could fall open when channel type was missing",
  "details" : "### Summary\n\nMattermost handlers could fall open when channel type was missing. In affected versions, a Mattermost event missing channel type metadata could continue without applying the intended DM policy decision.\n\nThis advisory is scoped to the named feature and configuration. It does not change OpenClaw's trusted-operator model: authenticated Gateway operators, installed plugins, and intentional local execution surfaces remain trusted unless a separate policy, approval, allowlist, sandbox, or auth boundary is crossed.\n\n### Impact\n\nWhen the affected feature is enabled and reachable, this could process a Mattermost event that should have been gated by channel policy. Practical impact depends on the operator's configuration and whether lower-trust input can reach that path.\n\n### Patched Versions\n\nThe first stable patched version is `2026.5.6`.\n\n### Mitigations\n\nkeep Mattermost bot access restricted and review channel metadata errors until patched. As general hardening, keep channel and tool allowlists narrow, avoid sharing one Gateway between mutually untrusted users, and disable the affected feature when it is not needed.",
  "severity" : [ {
    "type" : "CVSS_V3",
    "score" : "CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:L/A:N"
  }, {
    "type" : "CVSS_V4",
    "score" : "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"
  } ],
  "affected" : [ {
    "package" : {
      "ecosystem" : "npm",
      "name" : "openclaw"
    },
    "ranges" : [ {
      "type" : "ECOSYSTEM",
      "events" : [ {
        "introduced" : "0"
      }, {
        "fixed" : "2026.5.6"
      } ]
    } ],
    "database_specific" : {
      "last_known_affected_version_range" : "<= 2026.5.5"
    }
  } ],
  "references" : [ {
    "type" : "WEB",
    "url" : "https://github.com/openclaw/openclaw/security/advisories/GHSA-gp79-m99v-gjmh"
  }, {
    "type" : "ADVISORY",
    "url" : "https://nvd.nist.gov/vuln/detail/CVE-2026-53837"
  }, {
    "type" : "PACKAGE",
    "url" : "https://github.com/openclaw/openclaw"
  }, {
    "type" : "WEB",
    "url" : "https://www.vulncheck.com/advisories/openclaw-missing-channel-type-validation-in-mattermost-event-handlers"
  } ],
  "database_specific" : {
    "cwe_ids" : [ "CWE-636" ],
    "severity" : "MODERATE",
    "github_reviewed" : true,
    "github_reviewed_at" : "2026-07-02T16:45:14Z",
    "nvd_published_at" : null
  }
}