CVE-2026-4274— Insufficient authorization in shared channel membership sync grants team-level access instead of channel-level access
Get alerts for future matching vulnerabilitiesLog in to subscribe
I. Basic Information for CVE-2026-4274
Vulnerability Information
Have questions about the vulnerability? See if Shenlong's analysis helps!
View Shenlong Deep Dive ↗ Although we use advanced large model technology, its output may still contain inaccurate or outdated information.Shenlong tries to ensure data accuracy, but please verify and judge based on the actual situation.
Vulnerability Title
Insufficient authorization in shared channel membership sync grants team-level access instead of channel-level access
Source: NVD (National Vulnerability Database)
Vulnerability Description
Mattermost versions 11.2.x <= 11.2.2, 10.11.x <= 10.11.10, 11.4.x <= 11.4.0, 11.3.x <= 11.3.1 fail to restrict team-level access when processing membership sync from a remote cluster, which allows a malicious remote cluster to grant a user access to an entire private team instead of only the shared channel via sending crafted membership sync messages that trigger team membership assignment. Mattermost Advisory ID: MMSA-2026-00574
Source: NVD (National Vulnerability Database)
CVSS Information
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:L/I:L/A:N
Source: NVD (National Vulnerability Database)
Vulnerability Type
授权机制不正确
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 11.2.2及之前的11.2.x版本、10.11.10及之前的10.11.x版本、11.4.0及之前的11.4.x版本和11.3.1及之前的11.3.x版本存在安全漏洞，该漏洞源于处理来自远程集群的成员同步时未能限制团队级访问，可能导致恶意远程集群通过发送特制的成员同步消息授予用户访问整个私有团队的权限。
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 | 11.2.0 ~ 11.2.2 | - |
II. Public POCs for CVE-2026-4274
| # | POC Description | Source Link | Shenlong Link |
|---|
AI-Generated POCPremium
No public POC found.
Login to generate AI POCIII. Intelligence Information for CVE-2026-4274
请登录查看更多情报信息。
Same Patch Batch · Mattermost · 2026-03-26 · 8 CVEs total
| CVE-2026-3108 | 8.0 HIGH | Terminal Escape Injection in mmctl Report Posts Command |
| CVE-2026-3112 | 6.8 MEDIUM | Arbitrary File Read via Advanced Logging Support Packet |
| CVE-2026-3114 | 6.5 MEDIUM | Zip Bomb Denial of Service via Unrestricted Archive Decompression |
| CVE-2026-3113 | 5.0 MEDIUM | mmctl export download command doesn’t restrict permissions to created file to file owner |
| CVE-2026-3116 | 4.9 MEDIUM | Improper Input Validation in Zoom Plugin Webhook Handler |
| CVE-2026-3115 | 4.3 MEDIUM | Guest users can view group member IDs without respecting view restrictions |
| CVE-2026-3109 | 2.2 LOW | Missing timestamp validation in Zoom webhook handler |
IV. Related Vulnerabilities
Same product: Mattermost
- CVE-2026-3590
Race Condition in Guest Magic Link Authentication Allows Tok - CVE-2026-28741
CSRF Protection Bypass Allows Updating a User's Authenticati - CVE-2026-27769
Connected Workspaces: Malicious remote server can manipulate - CVE-2026-24661
Unbounded Request Body Read in MS Teams Plugin {{/changes}} - CVE-2026-21388
Unbounded Request Body Read in MS Teams Plugin {{/lifecycle}
Same vendor: Mattermost
- CVE-2026-3590
Race Condition in Guest Magic Link Authentication Allows Tok - CVE-2026-28741
CSRF Protection Bypass Allows Updating a User's Authenticati - CVE-2026-27769
Connected Workspaces: Malicious remote server can manipulate - CVE-2026-24661
Unbounded Request Body Read in MS Teams Plugin {{/changes}} - CVE-2026-21388
Unbounded Request Body Read in MS Teams Plugin {{/lifecycle}
Same weakness: CWE-863
- CVE-2026-42571
Privilege Escalation Attack affecting Pelican Web UI - CVE-2025-15633
HCL BigFix WebUI is affected by an improper authorization vu - CVE-2026-42296
Argo Workflows has incomplete fix for CVE-2026-31892: hostNe - CVE-2025-66170
Apache CloudStack: Any user can list backups that they shoul - CVE-2026-41903
FreeScout IDOR Vulnerability: PERM_EDIT_USERS allows modifyi
V. Comments for CVE-2026-4274
No comments yet