CVE-2026-6739

Mattermost: Delegated admins could patch protected default system roles

HIGH

7.2

CVSS Score

Published: June 12, 2026 at 03:49 PM UTC

Updated: June 18, 2026 at 03:45 PM UTC

2 products affected across 1 vendorMattermost ServerMattermost

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Severity

HIGH7.2

Exploit prediction

EPSS 0.3%

SSVC

No known exploit

Description

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 require system-level permission when patching protected default system roles, which allows authenticated users with delegated user-management permissions to escalate privileges by altering built-in role permissions via the role patch API.. Mattermost Advisory ID: MMSA-2026-00656

Affected

Our own answer: ranges merged, affected separated from platform-only, with confidence and review flags.

Mattermost Server · Mattermost

95%

10.11.0 ≤ v < 10.11.1711.5.0 ≤ v < 11.5.511.6.0 ≤ v < 11.6.2

Affected range stops below 10.11.17, so it looks safe — our inference, not a vendor statement

Affected range stops below 11.5.5, so it looks safe — our inference, not a vendor statement

Affected range stops below 11.6.2, so it looks safe — our inference, not a vendor statement

Mattermost · Mattermost

60%

10.11.0 ≤ v ≤ 10.11.1510.11.0 ≤ v ≤ 10.11.1611.5.0 ≤ v ≤ 11.5.411.6.0 ≤ v ≤ 11.6.110.11.0 11.5.0 11.6.0

Vendor states this is fixed in 10.11.16 (unaffected)

Vendor states this is fixed in 10.11.17 (unaffected)

Vendor states this is fixed in 11.5.5 (unaffected)

Vendor states this is fixed in 11.6.2 (unaffected)

Vendor states this is fixed in 11.7.0 (unaffected)

Remediation

No guide yet

No remediation guidance has been written for this CVE yet. What the record does show:

Patch and advisory references

https://mattermost.com/security-updates

References (1)

Vendor Advisory

Source: cverecord

https://mattermost.com/security-updates

SSVC — Action Prioritization

SSVCNo known exploitNot automatableTotal impact

SSVC signals action urgency (what to patch first), separate from CVSS which measures severity.

CVSS

7.2HIGH[email protected]

Attack Vector: NETWORK
Complexity: LOW
Privileges: HIGH
User Interaction: NONE
Scope: UNCHANGED
Confidentiality: HIGH
Integrity: HIGH
Availability: HIGH

Vector?

Quick Info

StatusANALYZED

CWE

CWE-863

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