HOMEVULNERABILITIESCVE-2026-4635
MEDIUM

CVE-2026-4635

CWE-362Published: May 22, 2026· Updated: May 22, 2026

5.3
CVSS v3.1
EPSS:0.04%probability of exploitation in 30 daysPercentile:10.8th

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 archive the channel before removing persistent notifications which allows authenticated user to crash the server via timing the creation of persistent notification message between the server deleting existing persistent notifications and archiving the channel.. Mattermost Advisory ID: MMSA-2026-00637

NVD Source

Technical Analysis

CVE-2026-4635 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 availability disruption (denial of service), with a CVSS base score of 5.3.

CVSS v3.1 Vector Breakdown

Exploitability
Attack VectorNetwork
Attack ComplexityHigh
Privileges Req.Low
User InteractionNone
ScopeUnchanged
Impact
ConfidentialityNone
IntegrityNone
AvailabilityHigh
CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:N/I:N/A:H

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-2026-4635
CVSS Score5.3 / 10
SeverityMEDIUM
WeaknessCWE-362
CISA KEVNo
EPSS (30d)0.04%
Affected1 vendor
PublishedMay 22, 2026

Related CVEs (CWE-362)

CVE-2026-5902
9.8
CVE-2025-13036
9.2
CVE-2025-10263
9.1
CVE-2025-32991
9.0
CVE-2026-20677
9.0
CVE-2026-44693
8.8

Recommended Actions

  • →Apply vendor patches immediately
  • →Monitor CVE-2026-4635 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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