HOMEVULNERABILITIESCVE-2026-6957
MEDIUM

CVE-2026-6957

CWE-22Published: May 27, 2026· Updated: Jun 2, 2026

4.9
CVSS v3.1
EPSS:0.04%probability of exploitation in 30 daysPercentile:13.5th

Official Description

Mattermost Plugins versions <=1.1.5 fail to sanitize filenames received from federated peers before using them to construct export destination paths, which allows an administrator of a remote federated Mattermost server to write files to arbitrary locations within the target server's filestore via a malicious filename delivered through the shared-channel attachment sync protocol. Mattermost Advisory ID: MMSA-2026-00659

NVD Source

Technical Analysis

CVE-2026-6957 can be exploited remotely over the network without requiring physical or adjacent access, significantly expanding the attack surface for threat actors.

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

A successful exploit results in full integrity compromise (data manipulation), with a CVSS base score of 4.9.

CVSS v3.1 Vector Breakdown

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

Affected Vendors & Products

mattermost1 product
legal hold
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-2026-6957
CVSS Score4.9 / 10
SeverityMEDIUM
WeaknessCWE-22
CISA KEVNo
EPSS (30d)0.04%
Affected1 vendor
PublishedMay 27, 2026

Related CVEs (CWE-22)

CVE-2026-11414
10.0
CVE-2026-22557
10.0
CVE-2026-41211
10.0
CVE-2026-11420
10.0
CVE-2026-2731
10.0
CVE-2025-64075
10.0

Recommended Actions

  • →Apply vendor patches immediately
  • →Monitor CVE-2026-6957 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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