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CVE-2026-28732

Slash command trigger-word update allowed command hijacking

Published: May 18, 2026Updated: May 19, 2026 Sources: CVE List NVDCWE-863
NVD MITRE
4.3CVSSMEDIUM
EPSS Score
0.2%
Top 95.3%
CISA KEV
Not in KEV
Exploits
No Known Exploits
Remediation
Patch Available

Description

Mattermost versions 11.5.x <= 11.5.1, 10.11.x <= 10.11.13, 11.4.x <= 11.4.3 Fail to enforce slash command trigger-word uniqueness during command updates which allows an authenticated team member with Manage Own Slash Commands permission to hijack and impersonate existing system or custom slash commands via editing their own slash command trigger to an already-registered trigger through the command update API. Mattermost Advisory ID: MMSA-2026-00597

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
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Weaknesses

CWE-863

Affected Products

MattermostMattermost
On-premWeb App
Communications / messaging-chat
mattermost servermattermost
On-premWeb App
Communications / messaging-chat
mattermostcommercialUSCommunications

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

Timeline

Published
May 18, 2026
Last Updated
May 19, 2026

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