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Home/Vulnerability/CVE-2026-6046

CVE-2026-6046

Plugin bot username conflict allows user account to be used as bot identity in Mattermost Server

Published: Jun 12, 2026Updated: Jun 12, 2026 Sources: CVE List NVD
NVD MITRE
5.3CVSS
MEDIUM

Mattermost versions 11.6.x <= 11.6.1, 11.5.x <= 11.5.4, 10.11.x <= 10.11.15, 10.11.x <= 10.11.16 fail to validate that a username returned during bot registration belongs to a bot account, which allows an unprivileged attacker to intercept private messages sent by plugins via direct message channels by pre-registering a user account with a predictable plugin bot username.. Mattermost Advisory ID: MMSA-2026-00649

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

CVSS Vector Breakdown

AV:NAC:HPR:LUI:NS:UC:HI:NA:N
Exploitability
AV:NAttack Vector
Network
AC:HAttack Complexity
High
PR:LPrivileges Required
Low
UI:NUser Interaction
None
Scope
S:UScope
Unchanged
Impact
C:HConfidentiality
High
I:NIntegrity
None
A:NAvailability
None

Weaknesses

CWE-200

Affected Products

Mattermost
Mattermost
Communications / messaging-chat
mattermostcommercialUSCommunicationsaka mattermost server, mattermost desktop

Attack Graph

Products CVE Techniques Tactics

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Exploitability

Official Patch Available

MITRE ATT&CK

1 technique
Collection
View detailed technique mapping

References

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

Timeline

Published
Jun 12, 2026
Last Updated
Jun 12, 2026

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