GHSA-fg35-5rf6-qg3g

Source

https://github.com/advisories/GHSA-fg35-5rf6-qg3g

Import Source

https://github.com/github/advisory-database/blob/main/advisories/github-reviewed/2026/03/GHSA-fg35-5rf6-qg3g/GHSA-fg35-5rf6-qg3g.json

JSON Data

https://api.osv.dev/v1/vulns/GHSA-fg35-5rf6-qg3g

Aliases

Published

2026-03-25T18:31:53Z

Modified

2026-06-25T19:56:08Z

Severity

5.7 (Medium) CVSS_V3 - CVSS:3.1/AV:N/AC:H/PR:H/UI:R/S:U/C:H/I:H/A:N CVSS Calculator

Summary

Mattermost allows attackers to take over arbitrary user accounts via overly permissive substring matching flaw

Details

Mattermost versions 11.4.x <= 11.4.0, 11.3.x <= 11.3.1, 11.2.x <= 11.2.3, 10.11.x <= 10.11.11 fail to properly validate user identity in the OpenID {{IsSameUser()}} comparison logic, which allows an attacker to take over arbitrary user accounts via an overly permissive substring matching flaw in the user discovery flow. Mattermost Advisory ID: MMSA-2026-00590

Database specific

{
    "cwe_ids":  [
        "CWE-303"
    ],
    "github_reviewed":  true,
    "github_reviewed_at":  "2026-03-31T05:19:17Z",
    "nvd_published_at":  "2026-03-25T17:16:56Z",
    "severity":  "MODERATE"
}

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

11.4.0-rc1

Fixed

11.4.1

Database specific

source

"https://github.com/github/advisory-database/blob/main/advisories/github-reviewed/2026/03/GHSA-fg35-5rf6-qg3g/GHSA-fg35-5rf6-qg3g.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

11.3.0-rc1

Fixed

11.3.2

Database specific

source

"https://github.com/github/advisory-database/blob/main/advisories/github-reviewed/2026/03/GHSA-fg35-5rf6-qg3g/GHSA-fg35-5rf6-qg3g.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

11.2.0-rc1

Fixed

11.2.4

Database specific

source

"https://github.com/github/advisory-database/blob/main/advisories/github-reviewed/2026/03/GHSA-fg35-5rf6-qg3g/GHSA-fg35-5rf6-qg3g.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-rc1

Fixed

10.11.12

Database specific

last_known_affected_version_range

"< 10.11.2"

source

"https://github.com/github/advisory-database/blob/main/advisories/github-reviewed/2026/03/GHSA-fg35-5rf6-qg3g/GHSA-fg35-5rf6-qg3g.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

8.0.0-20260105080200-d27a2195068d

Fixed

8.0.0-20260217110922-b7d4a1f1f59b

Database specific

source

"https://github.com/github/advisory-database/blob/main/advisories/github-reviewed/2026/03/GHSA-fg35-5rf6-qg3g/GHSA-fg35-5rf6-qg3g.json"