HOMEVULNERABILITIESCVE-2026-4273
MEDIUM

CVE-2026-4273

CWE-863Published: May 18, 2026· Updated: May 19, 2026

4.3
CVSS v3.1
EPSS:0.03%probability of exploitation in 30 daysPercentile:8.5th

Official Description

Mattermost versions 11.5.x <= 11.5.1, 10.11.x <= 10.11.13 fail to validate that the RefreshedToken differs from the original invite token during remote cluster invite confirmation which allows an authenticated attacker to bypass token rotation and reuse the original invite token via sending a crafted invite confirmation with a RefreshedToken matching the original token. Mattermost Advisory ID: MMSA-2026-00575

NVD Source

Technical Analysis

CVE-2026-4273 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
ConfidentialityNone
IntegrityLow
AvailabilityNone
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/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-2026-4273
CVSS Score4.3 / 10
SeverityMEDIUM
WeaknessCWE-863
CISA KEVNo
EPSS (30d)0.03%
Affected1 vendor
PublishedMay 18, 2026

Related CVEs (CWE-863)

CVE-2026-44330
10.0
CVE-2026-48303
10.0
CVE-2026-48286
10.0
CVE-2026-41283
9.9
CVE-2026-28466
9.9
CVE-2026-41050
9.9

Recommended Actions

  • →Apply vendor patches immediately
  • →Monitor CVE-2026-4273 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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