HOMEVULNERABILITIESCVE-2026-4274
MEDIUM

CVE-2026-4274

CWE-863Published: March 26, 2026· Updated: Mar 26, 2026

5.4
CVSS v3.1
EPSS:0.03%probability of exploitation in 30 daysPercentile:7.3th

Official 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

NVD Source

Technical Analysis

CVE-2026-4274 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.

CVSS v3.1 Vector Breakdown

Exploitability
Attack VectorNetwork
Attack ComplexityLow
Privileges Req.Low
User InteractionNone
ScopeUnchanged
Impact
ConfidentialityLow
IntegrityLow
AvailabilityNone
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:L/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
External links open in a new tab. Always verify in a controlled environment before use.

Official Patches & Advisories

ADVISORYhttps://mattermost.com/security-updates

All References (1)

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

Quick Facts

CVE IDCVE-2026-4274
CVSS Score5.4 / 10
SeverityMEDIUM
WeaknessCWE-863
CISA KEVNo
EPSS (30d)0.03%
Affected1 vendor
PublishedMar 26, 2026

Related CVEs (CWE-863)

CVE-2026-48303
10.0
CVE-2026-44330
10.0
CVE-2026-48286
10.0
CVE-2026-41283
9.9
CVE-2026-41050
9.9
CVE-2026-43948
9.9

Recommended Actions

  • →Apply vendor patches immediately
  • →Monitor CVE-2026-4274 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.
← All Vulnerabilities·Search for CVE-2026-4274·NVD