CVE-2026-6334 | BDVDB-2026-333776 Detail

MattermostMattermost

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

Impact#

Per CVSS v3.1: confidentiality impact low, integrity impact low, availability impact none. Attack vector: network.

Weaknesses#

CWE-305 – Authentication Bypass by Primary Weakness

References#

https://mattermost.com/security-updates

Exploit#

No public exploit known

History#

Version 12026-05-18Record published in the CVE List.

Published

Published: 2026-05-18
Last modified: 2026-05-18

Vendor information

Vendor: Mattermost
Product: Mattermost

All Mattermost vulnerabilities

Score

3.1 Low

EPSS

less than 1%, Very Low

Estimated chance of exploitation in the next 30 days. EPSS percentile: 1.7.

KEV

Not listed in the CISA Known Exploited Vulnerabilities catalog.

Impact

Not classified

Action

No specific action is recorded in the source data. Check the references for vendor guidance.

Affected Systems

Vulnerable
>= 11.5.0 and <= 11.5.1
Fixed
Not stated
Vulnerable
>= 10.11.0 and <= 10.11.13
Fixed
Not stated
Vulnerable
Not stated
Fixed
11.6.0
Vulnerable
Not stated
Fixed
11.5.2
Vulnerable
Not stated
Fixed
10.11.14

Scoring System

CVSS v4.0

Not available

CVSS v3.1

3.1 Low

CVSS:3.1/AV:N/AC:H/PR:H/UI:R/S:U/C:L/I:L/A:N

Metric breakdown
Attack Vector	Network
Attack Complexity	High
Privileges Required	High
User Interaction	Required
Scope	Unchanged
Confidentiality	Low
Integrity	Low
Availability	None

CVSS v3.0

Not available

CVSS v2

Not available

Source: CVE List v5 (record); CISA KEV (kev, action); FIRST EPSS (epss).