CVE-2026-3473
📛 CVE Title
Improper file ownership validation in the Boards API allows unauthorised file access
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
Overview
- State
- PUBLISHED
- Assigner (CNA)
- Mattermost
- CVSS severity
- MEDIUM
- CVSS score
- 5.9 / 10
- CVSS vector
CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:H/I:L/A:N- Effective score
- 5.9 / 10 MEDIUM source: CNA overview
- CWE(s)
-
CWE-639 - Reserved
- 2026-03-03
- Published
- 2026-05-22 10:27 UTC
- Last updated
- 2026-05-22 12:12 UTC
- Source
- https://raw.githubusercontent.com/CVEProject/cvelistV5/main/cves/2026/3xxx/CVE-2026-3473.json
- Linked Threat
- CVE-2026-3473 — CVE-2026-3473
NVD triage scoring NVD CVE 2.0
Layer NVD adds on top of the CNA's CVE record — published / last-modified timestamps, exploitability / impact subscores, and the FIRST.org EPSS probability that this CVE will be exploited in the wild in the next 30 days.
- EPSS score
- 0.0003 (probability of exploitation in next 30 days)
- EPSS percentile
- 8.40% vs all CVEs — higher = more likely to be exploited, as of 2026-05-24
NVD / KEV / EPSS data refreshed 2026-05-25 00:22 UTC. Re-run the 🛰 Backfill from NVD button above to refresh.
European Union Vulnerability Database ENISA EUVD
ENISA's official EU repository for curated vulnerability intelligence. Carries a separate identifier (EUVD-YYYY-NNNN) and frequently exposes an earlier-published description + CVSS than NVD does.
- EUVD ID
-
EUVD-2026-31429 - Assigner
- Mattermost
- Published
- May 22, 2026, 10:27:02 AM
- Updated
- May 22, 2026, 12:12:49 PM
- EUVD base score (CVSS 3.1)
-
5.9 / 10
CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:H/I:L/A:N - EUVD-reported EPSS
- 0.0300
- Vendors
- Mattermost
- Products
-
Mattermost (10.11.0 ≤10.11.14)Mattermost (11.5.0 ≤11.5.3)Mattermost (11.6.0 ≤11.6.0)Mattermost (11.4.0 ≤11.4.4)
- Aliases
-
GHSA-7pf2-9c95-w332
ENISA 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
EUVD references (1)
Affected products (1)
| Vendor | Product | Versions | Platforms |
|---|---|---|---|
| Mattermost | Mattermost |
11.6.0 (affected),
11.5.0 (affected),
11.4.0 (affected),
10.11.0 (affected),
11.7.0 (unaffected),
11.6.1 (unaffected),
11.5.4 (unaffected),
11.4.5 (unaffected),
10.11.15 (unaffected)
|
— |
Vendor references (1)
References embedded in the original CVE record by the assigning CNA.
- MMSA-2026-00620 vendor-advisory
Web references (4)
DuckDuckGo results ranked by threat-intel / vendor advisory domains. Generated by the 🔎 Find references (web) button above — same flow as the Remediations search.
- https://www.first.org/epss/ tenable:www.first.org
- https://mattermost.com/security-updates tenable:mattermost.com
- https://nvd.nist.gov/vuln/detail/CVE-2026-3473 tenable:nvd.nist.gov
- https://www.cve.org/CVERecord?id=CVE-2026-3473 tenable:www.cve.org
Remediations (15)
Remediations are stored against the linked Threat row; the list below is deduplicated across both pages.
-
web:community.ui.com
Published: May 21, 2026 Updated: May 22, 2026 Version: 1.1 Revision: 1.1 Summary 1 of 5 A malicious actor with access to the network and high privileges could exploit an Improper Input Validation vulnerability found in UniFi OS devices to execute a Command Injection. Affected Products: UniFi OS Server (Version 5.0.6 and earlier) Mitigation : Update your UniFi OS Server to Version 5.0.8 or later ...
2026-05-26 03:10 UTC -
web:cyberinsider.com
Microsoft fixes 83 vulnerabilities in Windows 11 with the March 2026 Patch Tuesday update, including two publicly disclosed zero-day flaws.
2026-05-26 03:10 UTC -
web:cybersecuritynews.com
Microsoft released its March 2026 Patch Tuesday security update on March 10, 2026 , addressing 78 vulnerabilities across Windows, Microsoft Office, Azure, SQL Server, and .NET. The update includes one actively exploited zero-day vulnerability and multiple Critical-rated flaws demanding immediate attention from security teams. The most urgent fix this month is CVE - 2026 -21262, the sole zero-day ...
2026-05-26 03:10 UTC -
web:nvd.nist.gov
An official website of the United States government Here's how you know
2026-05-26 03:10 UTC -
web:portal.msrc.microsoft.com
The Security Update Guide provides information on the latest Microsoft security updates, helping users understand and address potential vulnerabilities effectively.
2026-05-26 03:10 UTC -
web:support.esri.com
The C version of this patch also includes additional bug fixes not related to security, refer to the updated Issues Addressed with this Patch section for the latest details. Important Note - April 20, 2026 : The 11.4 version of the Portal for ArcGIS Security 2026 Update 1 Patch is now available.
2026-05-26 03:10 UTC -
web:windowsreport.com
Microsoft has released its May 2026 Patch Tuesday updates for Windows 11 and Windows 10, shipping as KB5089549 and KB5087544. The updates include fixes for more than 130 security vulnerabilities across Windows, Office, SharePoint, DNS components, and core system services, as Bleeping Computer writes. While no publicly disclosed zero-day vulnerabilities were reported this month, the […]
2026-05-26 03:10 UTC -
web:www.oracle.com
This Critical Patch Update contains 481 new security patches across the product families listed below. Please note that an MOS note summarizing the content of this Critical Patch Update and other Oracle Software Security Assurance activities is located at April 2026 Critical Patch Update: Executive Summary and Analysis.
2026-05-26 03:10 UTC -
web:www.windowslatest.com
Windows 11 March 2026 Patch Tuesday update adds Emoji 16.0, Sysmon, network speed test, reliability improvements, and security fixes.
2026-05-26 03:10 UTC -
web:zecurit.com
Get the complete breakdown of Microsoft's May 2026 Patch Tuesday. We analyze the latest security updates and all critical CVEs .
2026-05-26 03:10 UTC -
web:blackswan-cybersecurity.com
Cloud Files API activity originating outside legitimate OneDrive/sync processes. Mitigation Steps: Apply all Windows updates immediately (monitor MSRC for an emergency RedSun-specific patch . None released as of April 17, 2026 ). Supplement Defender with a secondary EDR solution (e.g., Huntress) capable of detecting Defender bypasses.
2026-06-03 22:33 UTC -
web:cvetodo.com
How do I fix CVE-2026-3473 ? To remediate CVE-2026-3473 : Check Mattermost's security advisories for official patches and updates. Update Mattermost to the latest patched version. Review the references section below for vendor advisories and mitigation guidance. What is the CVSS score of CVE-2026-3473 ?
2026-06-03 22:33 UTC -
web:nvd.nist.gov
Description Use after free in Network in Google Chrome prior to 148..7778.216 allowed a remote attacker to execute arbitrary code inside a sandbox via a crafted HTML page. (Chromium security severity: Critical)
2026-06-03 22:33 UTC -
web:www.cisecurity.org
<p>Multiple vulnerabilities have been discovered in Microsoft products, the most severe of which could allow for remote code execution. Successful exploitation of the most severe of these vulnerabilities could result in an attacker gaining the same privileges as the logged-on user. Depending on the privileges associated with the user, an attacker could then install programs; view, change, or ...
2026-06-03 22:33 UTC -
web:www.crowdstrike.com
Microsoft's March 2026 Patch Tuesday addresses 82 CVEs , featuring eight Critical vulnerabilities.
2026-06-03 22:33 UTC
AI Forensic Analysis
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Raw JSON
The full cvelistV5 record. Download as CVE-2026-3473.json.
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