CVE-2026-3473— Improper file ownership validation in the Boards API allows unauthorised file access
Possible ATT&CK Techniques 1AI
T1530 · Data from Cloud StorageAffected Version Matrix 9
| Vendor | Product | Version Range | Status |
|---|---|---|---|
| Mattermost | Mattermost | 11.6.0≤ 11.6.0 | affected |
11.5.0≤ 11.5.3 | affected | ||
11.4.0≤ 11.4.4 | affected | ||
10.11.0≤ 10.11.14 | affected | ||
11.7.0 | unaffected | ||
11.6.1 | unaffected | ||
11.5.4 | unaffected | ||
11.4.5 | unaffected | ||
| … +1 more rows | |||
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I. Basic Information for CVE-2026-3473
Vulnerability Information
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Vulnerability Title
Improper file ownership validation in the Boards API allows unauthorised file access
Source: NVD (National Vulnerability Database)
Vulnerability Description
Mattermost versions 11.6.x <= 11.6.0, 11.5.x <= 11.5.3, 11.4.x <= 11.4.4, 10.11.x <= 10.11.14 fail to validate file ownership and access control, which allows an authenticated user to access and download files belonging to other users or teams via crafted Boards API requests using valid file IDs.. Mattermost Advisory ID: MMSA-2026-00620
Source: NVD (National Vulnerability Database)
CVSS Information
CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:H/I:L/A:N
Source: NVD (National Vulnerability Database)
Vulnerability Type
通过用户控制密钥绕过授权机制
Source: NVD (National Vulnerability Database)
Affected Products
| Vendor | Product | Affected Versions | CPE | Subscribe |
|---|---|---|---|---|
| Mattermost | Mattermost | 11.6.0 ~ 11.6.0 | - |
II. Public POCs for CVE-2026-3473
| # | POC Description | Source Link | Shenlong Link |
|---|
AI-Generated POCPremium
No public POC found.
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Same Patch Batch · Mattermost · 2026-05-22 · 8 CVEs total
| CVE-2026-5740 | 7.5 HIGH | Unauthenticated WebSocket binary frame causes denial of service in Mattermost Server |
| CVE-2026-4635 | 6.5 MEDIUM | Persistent notification timing attack causing server denial of service |
| CVE-2026-5755 | 6.5 MEDIUM | Denial of service via crafted TIFF file upload |
| CVE-2026-28735 | 5.4 MEDIUM | GitHub OAuth Scope Validation |
| CVE-2026-5308 | 4.9 MEDIUM | Missing request body size limits on Zoom plugin HTTP endpoints |
| CVE-2026-4646 | 4.3 MEDIUM | Insufficient input validation in GitHub plugin API causes denial of service |
| CVE-2026-3636 | 4.3 MEDIUM | Sanitize team member data returned by API |
IV. Related Vulnerabilities
Same product: Mattermost
- CVE-2026-28735
GitHub OAuth Scope Validation - CVE-2026-4635
Persistent notification timing attack causing server denial - CVE-2026-4646
Insufficient input validation in GitHub plugin API causes de - CVE-2026-3636
Sanitize team member data returned by API - CVE-2026-5740
Unauthenticated WebSocket binary frame causes denial of serv
Same vendor: Mattermost
- CVE-2026-28735
GitHub OAuth Scope Validation - CVE-2026-4635
Persistent notification timing attack causing server denial - CVE-2026-4646
Insufficient input validation in GitHub plugin API causes de - CVE-2026-3636
Sanitize team member data returned by API - CVE-2026-5740
Unauthenticated WebSocket binary frame causes denial of serv
Same weakness: CWE-639
- CVE-2026-35430
Azure Privileged Identity Management (PIM) Elevation of Priv - CVE-2026-39967
TypeBot: Cross-Typebot Result Data Access via Missing typebo - CVE-2026-28444
Typebot: IDOR in Result Logs Endpoint Allows Cross-Workspace - CVE-2026-9248
Devolutions Server越权漏洞影响2025及2026版本 - CVE-2026-8347
Concrete CMS 9.5.0 and below is vulnerable to IDOR + wrong-a
V. Comments for CVE-2026-3473
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