CVE-2025-27715: Github.com/mattermost/mattermost/server/v8 Mattermost Fail To Prompt For Vulnerability

LOW
Advisory Identifier: GHSA-cw7q-5cgc-h3h9
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CVSS 3.3
CWE-863
Published
Advisory Summary

CVE-2025-27715 is a LOW (CVSS 3.3) mattermost fail to prompt for vulnerability (CWE-863: Incorrect Authorization) affecting Github.com/mattermost/mattermost/server/v8 libraries in the Go ecosystem. The issue involves mattermost fail to prompt for explicit approval before adding a team admin to a private channel. Remediation is available by upgrading affected packages to version 9.11.9.

CVE-2025-27715 at a Glance

CVE Identifier CVE-2025-27715
GHSA Identifier GHSA-cw7q-5cgc-h3h9
Severity LOW
CVSS v3.1 Base Score 3.3
CWE Classification CWE-863: Incorrect Authorization
Affected Product Github.com/mattermost/mattermost/server/v8
Package Ecosystem Go
Published Date
Last Updated

Security Impact

CVSS: 3.3

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

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

How to Fix CVE-2025-27715

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: 9.11.9 
Upgrade github.com/mattermost/mattermost/server/v8 to 9.11.9
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-2025-27715, 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 9.11.9), 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 9.11.x <= 9.11.8 fail to prompt for explicit approval before adding a team admin to a private channel, which team admins to joining private channels via crafted permalink links without explicit consent from them.

CVE-2025-27715 Affected Github.com/mattermost/mattermost/server/v8 Versions

1 component(s)
Fixed Versions:
9.11.9
Product / Package Ecosystem Affected Versions Fixed Version
github.com/mattermost/mattermost/server/v8
golang/github.com/mattermost/mattermost/server/v8
Go
≥ 9.11.0
< 9.11.9
9.11.9

References

NVD — CVE-2025-27715 NVD
https://nvd.nist.gov/vuln/detail/CVE-2025-27715
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-2025-27715?
CVE-2025-27715 is a security vulnerability in Github.com/mattermost/mattermost/server/v8 involving Mattermost fail to prompt for explicit approval before adding a team admin to a private channel under CWE-863: Incorrect Authorization.
Which Github.com/mattermost/mattermost/server/v8 versions are affected?
Affected versions include releases prior to 9.11.9 across affected packages: github.com/mattermost/mattermost/server/v8.
What version fixes CVE-2025-27715?
Upgrading to 9.11.9 (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 9.11.9. Upgrade your dependency to 9.11.9 or later.
What is the CVSS score of CVE-2025-27715?
CVE-2025-27715 has a CVSS v3.1 base score of 3.3 (LOW) with vector string CVSS:3.1/AV:N/AC:H/PR:H/UI:N/S:U/C:L/I:L/A:N.
What CWE is associated with CVE-2025-27715?
CVE-2025-27715 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-2025-27715?
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-cw7q-5cgc-h3h9",
  "modified" : "2025-03-21T22:38:09Z",
  "published" : "2025-03-21T09:30:35Z",
  "aliases" : [ "CVE-2025-27715" ],
  "summary" : "Mattermost fail to prompt for explicit approval before adding a team admin to a private channel",
  "details" : "Mattermost versions 9.11.x <= 9.11.8 fail to prompt for explicit approval before adding a team admin to a private channel, which team admins to joining private channels via crafted permalink links without explicit consent from them.",
  "severity" : [ {
    "type" : "CVSS_V3",
    "score" : "CVSS:3.1/AV:N/AC:H/PR:H/UI:N/S:U/C:L/I:L/A:N"
  } ],
  "affected" : [ {
    "package" : {
      "ecosystem" : "Go",
      "name" : "github.com/mattermost/mattermost/server/v8"
    },
    "ranges" : [ {
      "type" : "ECOSYSTEM",
      "events" : [ {
        "introduced" : "9.11.0"
      }, {
        "fixed" : "9.11.9"
      } ]
    } ]
  } ],
  "references" : [ {
    "type" : "ADVISORY",
    "url" : "https://nvd.nist.gov/vuln/detail/CVE-2025-27715"
  }, {
    "type" : "PACKAGE",
    "url" : "https://github.com/mattermost/mattermost"
  }, {
    "type" : "WEB",
    "url" : "https://mattermost.com/security-updates"
  } ],
  "database_specific" : {
    "cwe_ids" : [ "CWE-863" ],
    "severity" : "LOW",
    "github_reviewed" : true,
    "github_reviewed_at" : "2025-03-21T22:38:08Z",
    "nvd_published_at" : "2025-03-21T09:15:13Z"
  }
}