Vulnerabilities in pkg:golang/github.com/mattermost/mattermost-plugin-playbooks

PACKAGE
Advisory Identifier: GHSA-m79q-8qf5-v622
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Advisory Summary

CVE-2026-6343 is a MODERATE (CVSS 4.3) mattermost doesn't check public/private permissions vulnerability (CWE-863: Incorrect Authorization) affecting Github.com/mattermost/mattermost/server/v8 libraries in the Go ecosystem. The issue involves mattermost doesn't check public/private permissions. Remediation is available by upgrading affected packages to version 11.5.2, 11.4.4, 10.11.14, 1.41.1-0.20260309184833-887d9cacb616.

6 Known Advisory Record(s)
Package Vulnerability Intelligence

pkg:golang/github.com/mattermost/mattermost-plugin-playbooks

6 Known Advisory Record(s)

Vulnerability advisories affecting package pkg:golang/github.com/mattermost/mattermost-plugin-playbooks. Select an advisory below to view technical details or fixes.

Advisory ID CVE / NVD Severity Summary
GHSA-m79q-8qf5-v622 CVE-2026-6343 MODERATE Mattermost doesn't check public/private permissions
GHSA-gvg4-jhmr-6j23 CVE-2026-4286 LOW Mattermost doesn't check if {{team_id}} was being changed when updating playbooks
GHSA-4pmx-622h-x359 CVE-2026-26304 MODERATE Mattermost fails to verify run_create permission for empty playbookId
GHSA-fr22-5377-f3p7 CVE-2025-41423 LOW Mattermost Playbooks fails to properly validate permissions
GHSA-3g36-gf7c-75qw CVE-2025-41395 MODERATE Mattermost Playbooks fails to properly validate the props used by the RetrospectivePost custom post type
GHSA-689c-xq7x-xjwf CVE-2025-35965 MODERATE Mattermost Playbooks fails to validate the uniqueness and quantity of task actions

CVE-2026-6343 at a Glance

CVE Identifier CVE-2026-6343
GHSA Identifier GHSA-m79q-8qf5-v622
Severity MODERATE
CVSS v3.1 Base Score 4.3
CWE Classification CWE-863: Incorrect Authorization
Affected Product Github.com/mattermost/mattermost/server/v8
Package Ecosystem Go
Published Date
Last Updated

Security Impact

CVSS: 4.3

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

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

How to Fix CVE-2026-6343

To remediate this vulnerability, upgrade all affected Github.com/mattermost/mattermost/server/v8 dependencies to a patched release. Both direct and transitive dependencies should be checked, as frameworks or security libraries may pull in vulnerable versions transitively.

github.com/mattermost/mattermost/server/v8 fixed: 11.5.2 
Upgrade github.com/mattermost/mattermost/server/v8 to 11.5.2
github.com/mattermost/mattermost/server/v8 fixed: 11.4.4 
Upgrade github.com/mattermost/mattermost/server/v8 to 11.4.4
github.com/mattermost/mattermost/server/v8 fixed: 10.11.14 
Upgrade github.com/mattermost/mattermost/server/v8 to 10.11.14
github.com/mattermost/mattermost-plugin-playbooks fixed: 1.41.1-0.20260309184833-887d9cacb616 
Upgrade github.com/mattermost/mattermost-plugin-playbooks to 1.41.1-0.20260309184833-887d9cacb616
Verify Direct and Transitive Dependencies

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

inspect dependencies for github.com/mattermost/mattermost/server/v8

How to Check if You Are Affected

To determine whether your application is affected by CVE-2026-6343, inspect your project dependencies for Github.com/mattermost/mattermost/server/v8:

inspect dependencies for github.com/mattermost/mattermost/server/v8

Analyze the terminal output to locate any version of Github.com/mattermost/mattermost/server/v8 in your dependency tree. If any resolved version matches the vulnerable ranges listed in the table below (for example, versions earlier than 11.5.2), your application is affected.

Note: Verify declared build manifests and deployed runtime container environments.

Technical Details

Vulnerability Mechanism & Technical Analysis

This vulnerability is classified under CWE-863: Incorrect Authorization, where the product performs an authorization check when an actor attempts to access a resource or perform an action, but it does not correctly perform the check. In Github.com/mattermost/mattermost/server/v8, 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

Mattermost versions 11.5.x <= 11.5.1, 10.11.x <= 10.11.13, 11.4.x <= 11.4.3 fail to check public/private permissions which allows members without these permissions to access public playbooks via /get.. Mattermost Advisory ID: MMSA-2026-00591

CVE-2026-6343 Affected Github.com/mattermost/mattermost/server/v8 Versions

4 component(s)
Fixed Versions:
11.5.211.4.410.11.141.41.1-0.20260309184833-887d9cacb616
Product / Package Ecosystem Affected Versions Fixed Version
github.com/mattermost/mattermost/server/v8
golang/github.com/mattermost/mattermost/server/v8
Go
≥ 11.5.0
< 11.5.2
11.5.2
github.com/mattermost/mattermost/server/v8
golang/github.com/mattermost/mattermost/server/v8
Go
≥ 11.4.0
< 11.4.4
11.4.4
github.com/mattermost/mattermost/server/v8
golang/github.com/mattermost/mattermost/server/v8
Go
≥ 10.11.0
< 10.11.14
10.11.14
github.com/mattermost/mattermost-plugin-playbooks
golang/github.com/mattermost/mattermost-plugin-playbooks
Go
< 1.41.1-0.20260309184833-887d9cacb616
1.41.1-0.20260309184833-887d9cacb616

References

NVD — CVE-2026-6343 NVD
https://nvd.nist.gov/vuln/detail/CVE-2026-6343
Security Fix Commit FIX COMMIT
https://github.com/mattermost/mattermost-plugin-playbooks/commit/887d9cacb61655d40f20ad9d6e35b408a127c380
Github.com/mattermost/mattermost/server/v8 Source Repository REPOSITORY
https://github.com/mattermost/mattermost
Github.com/mattermost/mattermost/server/v8 Security Information SECURITY
https://mattermost.com/security-updates

Frequently Asked Questions

What is CVE-2026-6343?
CVE-2026-6343 is a security vulnerability in Github.com/mattermost/mattermost/server/v8 involving Mattermost doesn't check public/private permissions under CWE-863: Incorrect Authorization.
Which Github.com/mattermost/mattermost/server/v8 versions are affected?
Affected versions include releases prior to 11.5.2, 11.4.4, 10.11.14, 1.41.1-0.20260309184833-887d9cacb616 across affected packages: github.com/mattermost/mattermost/server/v8, github.com/mattermost/mattermost-plugin-playbooks.
What version fixes CVE-2026-6343?
Upgrading to 11.5.2, 11.4.4, 10.11.14, 1.41.1-0.20260309184833-887d9cacb616 (or the latest patched release for your respective branch) resolves the vulnerability.
Is github.com/mattermost/mattermost/server/v8 affected?
Yes, github.com/mattermost/mattermost/server/v8 is affected in releases prior to 11.5.2, 11.4.4, 10.11.14. Upgrade your dependency to 11.5.2, 11.4.4, 10.11.14 or later.
Is github.com/mattermost/mattermost-plugin-playbooks affected?
Yes, github.com/mattermost/mattermost-plugin-playbooks is affected in releases prior to 1.41.1-0.20260309184833-887d9cacb616. Upgrade your dependency to 1.41.1-0.20260309184833-887d9cacb616 or later.
What is the CVSS score of CVE-2026-6343?
CVE-2026-6343 has a CVSS v3.1 base score of 4.3 (MODERATE) with vector string CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:L/I:N/A:N.
What CWE is associated with CVE-2026-6343?
CVE-2026-6343 is classified under CWE-863: Incorrect Authorization (The product performs an authorization check when an actor attempts to access a resource or perform an action, but it does not correctly perform the check.).
How can I check Go dependencies for CVE-2026-6343?
Run the dependency tree command: 'inspect dependencies for github.com/mattermost/mattermost/server/v8'. 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-m79q-8qf5-v622",
  "modified" : "2026-06-01T15:38:19Z",
  "published" : "2026-05-18T09:31:48Z",
  "aliases" : [ "CVE-2026-6343" ],
  "summary" : "Mattermost doesn't check public/private permissions",
  "details" : "Mattermost versions 11.5.x <= 11.5.1, 10.11.x <= 10.11.13, 11.4.x <= 11.4.3 fail to check public/private permissions which allows members without these permissions to access public playbooks via /get.. Mattermost Advisory ID: MMSA-2026-00591",
  "severity" : [ {
    "type" : "CVSS_V3",
    "score" : "CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:L/I:N/A:N"
  } ],
  "affected" : [ {
    "package" : {
      "ecosystem" : "Go",
      "name" : "github.com/mattermost/mattermost/server/v8"
    },
    "ranges" : [ {
      "type" : "ECOSYSTEM",
      "events" : [ {
        "introduced" : "11.5.0"
      }, {
        "fixed" : "11.5.2"
      } ]
    } ]
  }, {
    "package" : {
      "ecosystem" : "Go",
      "name" : "github.com/mattermost/mattermost/server/v8"
    },
    "ranges" : [ {
      "type" : "ECOSYSTEM",
      "events" : [ {
        "introduced" : "11.4.0"
      }, {
        "fixed" : "11.4.4"
      } ]
    } ]
  }, {
    "package" : {
      "ecosystem" : "Go",
      "name" : "github.com/mattermost/mattermost/server/v8"
    },
    "ranges" : [ {
      "type" : "ECOSYSTEM",
      "events" : [ {
        "introduced" : "10.11.0"
      }, {
        "fixed" : "10.11.14"
      } ]
    } ]
  }, {
    "package" : {
      "ecosystem" : "Go",
      "name" : "github.com/mattermost/mattermost-plugin-playbooks"
    },
    "ranges" : [ {
      "type" : "ECOSYSTEM",
      "events" : [ {
        "introduced" : "0"
      }, {
        "fixed" : "1.41.1-0.20260309184833-887d9cacb616"
      } ]
    } ]
  } ],
  "references" : [ {
    "type" : "ADVISORY",
    "url" : "https://nvd.nist.gov/vuln/detail/CVE-2026-6343"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/mattermost/mattermost-plugin-playbooks/commit/887d9cacb61655d40f20ad9d6e35b408a127c380"
  }, {
    "type" : "PACKAGE",
    "url" : "https://github.com/mattermost/mattermost"
  }, {
    "type" : "WEB",
    "url" : "https://mattermost.com/security-updates"
  } ],
  "database_specific" : {
    "cwe_ids" : [ "CWE-863" ],
    "severity" : "MODERATE",
    "github_reviewed" : true,
    "github_reviewed_at" : "2026-06-01T15:38:19Z",
    "nvd_published_at" : "2026-05-18T09:16:23Z"
  }
}