HOMEVULNERABILITIESCVE-2026-3473
HIGH

CVE-2026-3473

CWE-639Published: May 22, 2026· Updated: May 22, 2026

7.1
CVSS v3.1
EPSS:0.03%probability of exploitation in 30 daysPercentile:8.4th

Official 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

NVD Source

Technical Analysis

CVE-2026-3473 can be exploited remotely over the network without requiring physical or adjacent access, significantly expanding the attack surface for threat actors.

Exploitation requires low privileges, which limits the exposure to scenarios where an attacker has already gained initial access.

A successful exploit results in complete confidentiality breach (data exposure), with a CVSS base score of 7.1.

CVSS v3.1 Vector Breakdown

Exploitability
Attack VectorNetwork
Attack ComplexityLow
Privileges Req.Low
User InteractionNone
ScopeUnchanged
Impact
ConfidentialityHigh
IntegrityLow
AvailabilityNone
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:L/A:N

Affected Vendors & Products

mattermost1 product
mattermost server
Source: NVD CPE · 1 total CPE entries

Exploit & PoC Resources

NO KNOWN EXPLOITNo public exploit confirmed at this time
Exploit-DB
Offensive Security exploit database
GitHub PoC Search
Community PoC repositories
Rapid7 / Metasploit
Metasploit module search
PacketStorm
Security advisories & exploits
NVD Detail
Official NIST entry
MITRE CVE
CVE Program entry
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Official Patches & Advisories

ADVISORYhttps://mattermost.com/security-updates

All References (1)

→
https://mattermost.com/security-updatesVendor Advisory

Quick Facts

CVE IDCVE-2026-3473
CVSS Score7.1 / 10
SeverityHIGH
WeaknessCWE-639
CISA KEVNo
EPSS (30d)0.03%
Affected1 vendor
PublishedMay 22, 2026

Related CVEs (CWE-639)

CVE-2026-55255
KEV9.9
CVE-2026-45552
9.9
CVE-2026-29200
9.9
CVE-2026-52782
9.9
CVE-2026-41267
9.8
CVE-2018-25270
9.8

Recommended Actions

  • →Apply vendor patches immediately
  • →Monitor CVE-2026-3473 in threat intel feeds
  • →Review IDS/IPS signatures for exploitation attempts
Data sourced from NVD (NIST), CISA KEV, and EPSS (FIRST). Analysis generated by CTIWATCH.COM. CVE data is provided under the NVD usage policy.
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