GHSA-w9m8-p4cc-4qj9

Source

https://github.com/advisories/GHSA-w9m8-p4cc-4qj9

Import Source

https://github.com/github/advisory-database/blob/main/advisories/github-reviewed/2026/05/GHSA-w9m8-p4cc-4qj9/GHSA-w9m8-p4cc-4qj9.json

JSON Data

https://api.osv.dev/v1/vulns/GHSA-w9m8-p4cc-4qj9

Aliases

Published

2026-05-26T13:30:15Z

Modified

2026-07-07T16:11:10Z

Severity

7.5 (High) CVSS_V3 - CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H CVSS Calculator

Summary

Mattermost doesn't properly validate msgpack-encoded WebSocket frames before memory allocation

Details

Mattermost versions 11.6.x <= 11.6.0, 11.5.x <= 11.5.3, 11.4.x <= 11.4.4, 10.11.x <= 10.11.14 fail to properly validate msgpack-encoded WebSocket frames before memory allocation which allows an unauthenticated remote attacker to crash the server process and cause a full service outage for all users via a crafted binary WebSocket message sent to the public WebSocket endpoint.. Mattermost Advisory ID: MMSA-2026-00647

Database specific

{
    "cwe_ids":  [
        "CWE-789"
    ],
    "github_reviewed":  true,
    "github_reviewed_at":  "2026-06-29T22:52:00Z",
    "nvd_published_at":  "2026-05-22T11:16:23Z",
    "severity":  "HIGH"
}

References

Affected packages

github.com/mattermost/mattermost-server

Package

Name: github.com/mattermost/mattermost-server; View open source insights on deps.dev
Purl: pkg:golang/github.com/mattermost/mattermost-server

Affected ranges

Type: SEMVER
Events: Introduced

11.6.0

Fixed

11.6.1

Affected versions

11.*

11.6.0

Database specific

source

"https://github.com/github/advisory-database/blob/main/advisories/github-reviewed/2026/05/GHSA-w9m8-p4cc-4qj9/GHSA-w9m8-p4cc-4qj9.json"

github.com/mattermost/mattermost-server

Package

Name: github.com/mattermost/mattermost-server; View open source insights on deps.dev
Purl: pkg:golang/github.com/mattermost/mattermost-server

Affected ranges

Type: SEMVER
Events: Introduced

11.5.0

Fixed

11.5.4

Database specific

source

"https://github.com/github/advisory-database/blob/main/advisories/github-reviewed/2026/05/GHSA-w9m8-p4cc-4qj9/GHSA-w9m8-p4cc-4qj9.json"

github.com/mattermost/mattermost-server

Package

Name: github.com/mattermost/mattermost-server; View open source insights on deps.dev
Purl: pkg:golang/github.com/mattermost/mattermost-server

Affected ranges

Type: SEMVER
Events: Introduced

11.4.0

Fixed

11.4.5

Database specific

source

"https://github.com/github/advisory-database/blob/main/advisories/github-reviewed/2026/05/GHSA-w9m8-p4cc-4qj9/GHSA-w9m8-p4cc-4qj9.json"

github.com/mattermost/mattermost-server

Package

Name: github.com/mattermost/mattermost-server; View open source insights on deps.dev
Purl: pkg:golang/github.com/mattermost/mattermost-server

Affected ranges

Type: SEMVER
Events: Introduced

10.11.0

Fixed

10.11.15

Database specific

source

"https://github.com/github/advisory-database/blob/main/advisories/github-reviewed/2026/05/GHSA-w9m8-p4cc-4qj9/GHSA-w9m8-p4cc-4qj9.json"

github.com/mattermost/mattermost/server/v8

Package

Name: github.com/mattermost/mattermost/server/v8; View open source insights on deps.dev
Purl: pkg:golang/github.com/mattermost/mattermost/server/v8

Affected ranges

Type: SEMVER
Events: Introduced

0 Unknown introduced version / All previous versions are affected

Fixed

8.0.0-20260410202636-17939826efa2

Database specific

source

"https://github.com/github/advisory-database/blob/main/advisories/github-reviewed/2026/05/GHSA-w9m8-p4cc-4qj9/GHSA-w9m8-p4cc-4qj9.json"