CVE-2026-6334— OAuth authorization code client binding not enforced during token redemption in Mattermost
Possible ATT&CK Techniques 1AI
T1190 · Exploit Public-Facing ApplicationAffected Version Matrix 5
| Vendor | Product | Version Range | Status |
|---|---|---|---|
| Mattermost | Mattermost | 11.5.0≤ 11.5.1 | affected |
10.11.0≤ 10.11.13 | affected | ||
11.6.0 | unaffected | ||
11.5.2 | unaffected | ||
10.11.14 | unaffected |
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I. Basic Information for CVE-2026-6334
Vulnerability Information
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Vulnerability Title
OAuth authorization code client binding not enforced during token redemption in Mattermost
Source: NVD (National Vulnerability Database)
Vulnerability 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
Source: NVD (National Vulnerability Database)
CVSS Information
CVSS:3.1/AV:N/AC:H/PR:H/UI:R/S:U/C:L/I:L/A:N
Source: NVD (National Vulnerability Database)
Vulnerability Type
使用基本弱点进行的认证绕过
Source: NVD (National Vulnerability Database)
Vulnerability Title
Mattermost 安全漏洞
Source: CNNVD (China National Vulnerability Database)
Vulnerability Description
Mattermost是美国Mattermost公司的一个开源协作平台。 Mattermost 11.5.1及之前的11.5.x版本和10.11.13及之前的10.11.x版本存在安全漏洞，该漏洞源于OAuth授权码兑换流程中未强制客户端身份绑定，可能导致认证OAuth客户端通过特制令牌交换请求兑换颁发给不同客户端的授权码。
Source: CNNVD (China National Vulnerability Database)
CVSS Information
N/A
Source: CNNVD (China National Vulnerability Database)
Vulnerability Type
N/A
Source: CNNVD (China National Vulnerability Database)
Affected Products
| Vendor | Product | Affected Versions | CPE | Subscribe |
|---|---|---|---|---|
| Mattermost | Mattermost | 11.5.0 ~ 11.5.1 | - |
II. Public POCs for CVE-2026-6334
| # | POC Description | Source Link | Shenlong Link |
|---|
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Same Patch Batch · Mattermost · 2026-05-18 · 21 CVEs total
| CVE-2026-6346 | 8.7 HIGH | Sensitive credentials exposed in plaintext in Mattermost support packets |
| CVE-2026-6347 | 7.6 HIGH | Mattermost Calls plugin exposes TURN server credentials in plaintext in support packets |
| CVE-2026-3471 | 6.5 MEDIUM | Opening a window with {{javascript:alert()}} as URL causes crash in the Mattermost Desktop |
| CVE-2026-3117 | 6.5 MEDIUM | Instance and webhook GitLab plugin commands were able to be run by non-admin users |
| CVE-2026-5163 | 6.5 MEDIUM | Missing authorization check in AI message rewrite endpoint allows access to private thread |
| CVE-2026-6345 | 6.5 MEDIUM | Prevent password disclosure and force reset during Slack import |
| CVE-2026-28732 | 4.3 MEDIUM | Slash command trigger-word update allowed command hijacking |
| CVE-2026-6343 | 4.3 MEDIUM | Mattermost Playbooks Plugin fails to enforce view permissions in list endpoints, allowing |
| CVE-2026-28759 | 4.3 MEDIUM | Insufficient authorization in shared channel membership sync allows remote cluster to remo |
| CVE-2026-2325 | 4.3 MEDIUM | Improper Input Validation in MS Teams Meetings API Handler |
| CVE-2026-6339 | 4.3 MEDIUM | Missing request origin validation on burn-on-read reveal endpoint |
| CVE-2026-6340 | 4.3 MEDIUM | Memory Exhaustion via Malicious 7zip File Upload |
| CVE-2026-6341 | 4.3 MEDIUM | Incomplete group locking implementation |
| CVE-2026-6342 | 4.3 MEDIUM | Group prefix matching bypass for subscriptions |
| CVE-2026-3637 | 4.3 MEDIUM | Mattermost fails to enforce create_post permission when editing posts |
| CVE-2026-3495 | 3.8 LOW | Unescaped variables during error page composition |
| CVE-2026-4273 | 3.7 LOW | Insufficient token rotation validation in remote cluster invite confirmation |
| CVE-2026-4643 | 3.5 LOW | Calling window.close() from server-side content causes crash in the Mattermost Desktop App |
| CVE-2026-6333 | 3.5 LOW | SSRF via Host Header Spoofing in Custom Slash Commands |
| CVE-2026-4286 | 3.1 LOW | Playbooks Plugin fails to validate team transfers, allowing unauthorized removal of member |
IV. Related Vulnerabilities
Same product: Mattermost
- CVE-2026-4915
Server panic via outgoing webhook responses - CVE-2026-28735
GitHub OAuth Scope Validation - CVE-2026-4635
Persistent notification timing attack causing server denial - CVE-2026-3473
Improper file ownership validation in the Boards API allows - CVE-2026-4646
Insufficient input validation in GitHub plugin API causes de
Same vendor: Mattermost
- CVE-2026-4915
Server panic via outgoing webhook responses - CVE-2026-28735
GitHub OAuth Scope Validation - CVE-2026-4635
Persistent notification timing attack causing server denial - CVE-2026-3473
Improper file ownership validation in the Boards API allows - CVE-2026-4646
Insufficient input validation in GitHub plugin API causes de
Same weakness: CWE-305
- CVE-2026-9047
Devolutions Server 多因素认证绕过漏洞 - CVE-2026-41054
Missing exit out of permission check in haveged could lead t - CVE-2026-2652
Authentication Bypass in mlflow/mlflow - CVE-2026-6266
Aap-controller: aap-gateway: account hijacking and unauthori - CVE-2026-4670
Improper Authentication vulnerability in Progress MOVEit Aut
V. Comments for CVE-2026-6334
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