CVE-2026-2476: Github.com/mattermost/mattermost plugin msteams Mattermost Microsoft Teams Plugin Fails Vulnerability

HIGH
Advisory Identifier: GHSA-4ppj-6chv-5pgc
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CVSS 7.6
CWE-200
Published
Advisory Summary

CVE-2026-2476 is a HIGH (CVSS 7.6) mattermost microsoft teams plugin fails vulnerability (CWE-200: Exposure of Sensitive Information to an Unauthorized Actor) affecting Github.com/mattermost/mattermost plugin msteams libraries in the Go ecosystem. The issue involves mattermost microsoft teams plugin fails to properly mask sensitive configuration values. Remediation is available by upgrading affected packages to version 1.15.1-0.20260102165339-036c761bd3cb.

CVE-2026-2476 at a Glance

CVE Identifier CVE-2026-2476
GHSA Identifier GHSA-4ppj-6chv-5pgc
Severity HIGH
CVSS v3.1 Base Score 7.6
CWE Classification CWE-200: Exposure of Sensitive Information to an Unauthorized Actor
Affected Product Github.com/mattermost/mattermost plugin msteams
Package Ecosystem Go
Published Date
Last Updated

Security Impact

CVSS: 7.6

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

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

How to Fix CVE-2026-2476

To remediate this vulnerability, upgrade all affected Github.com/mattermost/mattermost plugin msteams 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-plugin-msteams fixed: 1.15.1-0.20260102165339-036c761bd3cb 
Upgrade github.com/mattermost/mattermost-plugin-msteams to 1.15.1-0.20260102165339-036c761bd3cb
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-plugin-msteams

How to Check if You Are Affected

To determine whether your application is affected by CVE-2026-2476, inspect your project dependencies for Github.com/mattermost/mattermost plugin msteams:

inspect dependencies for github.com/mattermost/mattermost-plugin-msteams

Analyze the terminal output to locate any version of Github.com/mattermost/mattermost plugin msteams in your dependency tree. If any resolved version matches the vulnerable ranges listed in the table below (for example, versions earlier than 1.15.1-0.20260102165339-036c761bd3cb), 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-200: Exposure of Sensitive Information to an Unauthorized Actor, where the product exposes sensitive information to an actor that is not explicitly authorized to have access to that information. In Github.com/mattermost/mattermost plugin msteams, 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 Plugins versions <=2.0.3.0 fail to properly mask sensitive configuration values which allows an attacker with access to support packets to obtain original plugin settings via exported configuration data. Mattermost Advisory ID: MMSA-2026-00606

CVE-2026-2476 Affected Github.com/mattermost/mattermost plugin msteams Versions

1 component(s)
Fixed Versions:
1.15.1-0.20260102165339-036c761bd3cb
Product / Package Ecosystem Affected Versions Fixed Version
github.com/mattermost/mattermost-plugin-msteams
golang/github.com/mattermost/mattermost-plugin-msteams
Go
< 1.15.1-0.20260102165339-036c761bd3cb
1.15.1-0.20260102165339-036c761bd3cb

References

NVD — CVE-2026-2476 NVD
https://nvd.nist.gov/vuln/detail/CVE-2026-2476
Security Fix Commit FIX COMMIT
https://github.com/mattermost/mattermost-plugin-msteams/commit/036c761bd3cb9ece92c17f2b151dfa906cebdcf6
Github.com/mattermost/mattermost plugin msteams Source Repository REPOSITORY
https://github.com/mattermost/mattermost-plugin-msteams
Github.com/mattermost/mattermost plugin msteams Security Information SECURITY
https://mattermost.com/security-updates

Frequently Asked Questions

What is CVE-2026-2476?
CVE-2026-2476 is a security vulnerability in Github.com/mattermost/mattermost plugin msteams involving Mattermost Microsoft Teams Plugin fails to properly mask sensitive configuration values under CWE-200: Exposure of Sensitive Information to an Unauthorized Actor.
Which Github.com/mattermost/mattermost plugin msteams versions are affected?
Affected versions include releases prior to 1.15.1-0.20260102165339-036c761bd3cb across affected packages: github.com/mattermost/mattermost-plugin-msteams.
What version fixes CVE-2026-2476?
Upgrading to 1.15.1-0.20260102165339-036c761bd3cb (or the latest patched release for your respective branch) resolves the vulnerability.
Is github.com/mattermost/mattermost-plugin-msteams affected?
Yes, github.com/mattermost/mattermost-plugin-msteams is affected in releases prior to 1.15.1-0.20260102165339-036c761bd3cb. Upgrade your dependency to 1.15.1-0.20260102165339-036c761bd3cb or later.
What is the CVSS score of CVE-2026-2476?
CVE-2026-2476 has a CVSS v3.1 base score of 7.6 (HIGH) with vector string CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:C/C:H/I:L/A:N.
What CWE is associated with CVE-2026-2476?
CVE-2026-2476 is classified under CWE-200: Exposure of Sensitive Information to an Unauthorized Actor (The product exposes sensitive information to an actor that is not explicitly authorized to have access to that information.).
How can I check Go dependencies for CVE-2026-2476?
Run the dependency tree command: 'inspect dependencies for github.com/mattermost/mattermost-plugin-msteams'. 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-4ppj-6chv-5pgc",
  "modified" : "2026-03-19T19:25:25Z",
  "published" : "2026-03-16T15:30:43Z",
  "aliases" : [ "CVE-2026-2476" ],
  "summary" : "Mattermost Microsoft Teams Plugin fails to properly mask sensitive configuration values",
  "details" : "Mattermost Plugins versions <=2.0.3.0 fail to properly mask sensitive configuration values which allows an attacker with access to support packets to obtain original plugin settings via exported configuration data. Mattermost Advisory ID: MMSA-2026-00606",
  "severity" : [ {
    "type" : "CVSS_V3",
    "score" : "CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:C/C:H/I:L/A:N"
  } ],
  "affected" : [ {
    "package" : {
      "ecosystem" : "Go",
      "name" : "github.com/mattermost/mattermost-plugin-msteams"
    },
    "ranges" : [ {
      "type" : "ECOSYSTEM",
      "events" : [ {
        "introduced" : "0"
      }, {
        "fixed" : "1.15.1-0.20260102165339-036c761bd3cb"
      } ]
    } ]
  } ],
  "references" : [ {
    "type" : "ADVISORY",
    "url" : "https://nvd.nist.gov/vuln/detail/CVE-2026-2476"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/mattermost/mattermost-plugin-msteams/commit/036c761bd3cb9ece92c17f2b151dfa906cebdcf6"
  }, {
    "type" : "PACKAGE",
    "url" : "https://github.com/mattermost/mattermost-plugin-msteams"
  }, {
    "type" : "WEB",
    "url" : "https://mattermost.com/security-updates"
  } ],
  "database_specific" : {
    "cwe_ids" : [ "CWE-200" ],
    "severity" : "HIGH",
    "github_reviewed" : true,
    "github_reviewed_at" : "2026-03-19T19:25:25Z",
    "nvd_published_at" : "2026-03-16T14:19:30Z"
  }
}