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CVE-2026-4055

Insufficient permission validation on cross-team playbook run creation

Published: May 21, 2026Updated: May 21, 2026 Sources: CVE List
NVD MITRE
4.3CVSS
MEDIUM

Mattermost versions 11.5.x <= 11.5.1 fail to validate team-level run_create permission against the target team when creating a playbook run which allows an authenticated team member to create runs in teams where they lack permission via specifying a different team ID in the run creation API request. Mattermost Advisory ID: MMSA-2026-00629

EPSS Score
N/A
CISA KEV
Not in KEV
Exploits
No Known Exploits
Remediation
Patch Available

CVSS Vector Breakdown

AV:NAC:LPR:LUI:NS:UC:NI:LA:N
Exploitability
AV:NAttack Vector
Network
AC:LAttack Complexity
Low
PR:LPrivileges Required
Low
UI:NUser Interaction
None
Scope
S:UScope
Unchanged
Impact
C:NConfidentiality
None
I:LIntegrity
Low
A:NAvailability
None

Weaknesses

CWE-863CWE-863: Incorrect Authorization

Affected Products

Mattermost
Mattermost

Attack Graph

Products CVE Techniques Tactics

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Exploitability

Official Patch Available

MITRE ATT&CK

2 techniques
Initial Access
View detailed technique mapping

References

https://mattermost.com/security-updates
mattermost.com

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