CVE-2026-6334
LOW3.1EPSS 0.03%Mattermost doesn't enforce client identity binding during the OAuth authorization code redemption flow
Published: 5/18/2026Modified: 6/1/2026
Description
Mattermost versions 11.5.x <= 11.5.1, 10.11.x <= 10.11.13 fail to enforce client identity binding during the OAuth authorization code redemption flow which allows an authenticated OAuth client to redeem authorization codes issued to a different client via a crafted token exchange request.. Mattermost Advisory ID: MMSA-2026-00570
Affected packages (2)
- Go/github.com/mattermost/mattermost-serverfrom 0, < 5.3.2-0.20260318173148-e9ae890a013b
- Go/github.com/mattermost/mattermost/server/v8>= 11.5.0, < 11.5.2
CVSS scores
| Source | Version | Severity | Vector |
|---|---|---|---|
| osv | CVSS 3.1 | LOW3.1 | CVSS:3.1/AV:N/AC:H/PR:H/UI:R/S:U/C:L/I:L/A:N |