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Vulnerability IntelligenceCVE-2026-6334

CVE-2026-6334

LOW3.1

OAuth authorization code client binding not enforced during token redemption in Mattermost

Published May 18, 2026

Modified 4 days ago

Details

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

References

https://mattermost.com/security-updates

https://www.cve.org/CVERecord?id=CVE-2026-6334

CVSS Analysis

CVSS v3.1

3.1

Exploitability

Attack Vector

NetworkAV:N

Attack Complexity

HighAC:H

Privileges Required

HighPR:H

User Interaction

RequiredUI:R

Scope

Scope

UnchangedS:U

Impact

Confidentiality

LowC:L

Integrity

LowI:L

Availability

NoneA:N

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

Weakness Type (CWE)

Other

Ecosystems

Timeline

PublishedMay 18, 2026

ModifiedMay 18, 2026

CVE-2026-6334 | Mondoo Vulnerability Intelligence