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Fencer Vulns
medium 6.7

CVE-2026-6739 json

Mattermost: Delegated admins could patch protected default system roles

published 2026-06-12 4 mo ago modified 2026-09-10 1 mo ago also GHSA-m2w9-h2mm-79qr , GO-2026-6285 , EUVD-2026-36499

cvss
6.7
version 3.1, CNA
cisa kev
Not listed
not in CISA's catalog
epss
0.3%
EPSS 0.3% chance of exploitation in 30 days, percentile 17%
public exploits
0
none known

Summary

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

Patch / fix

  • go github.com/mattermost/mattermost-server 10.11.17, 10.11.17+incompatible, 11.5.5, 11.5.5+incompatible, 11.6.1, 11.6.1+incompatible
  • go github.com/mattermost/mattermost/server/v8 8.0.0-20260501142004-99b73d4c4acf
  • Mattermost Mattermost 10.11.16, 10.11.17, 11.5.5, 11.6.2, 11.7.0
  • govulncheck-vulndb SLES for SAP applications 16.0, SLES 16.0 0.0.20260827T195228-160000.1.1

suse advisories SUSE-SU-2026:23625-1

  • govulncheck-vulndb openSUSE Leap 16.0 0.0.20260827T195228-160000.1.1

opensuse advisories openSUSE-SU-2026:21761-1

CISA SSVC

Exploitation
none
Automatable
no
Technical impact
total
Assessed
4 mo ago

Exploit prediction

0.26% chance of exploitation in the next 30 days, higher than 17% of all scored CVEs (FIRST EPSS, 2026-11-08).

CVSS scores

assigned by version score vector
CNA 3.1 6.7 CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:U/C:H/I:H/A:L
NVD 3.1 7.2 CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:U/C:H/I:H/A:H
GitHub 3.1 6.7 CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:U/C:H/I:H/A:L

Affected packages

ecosystem package affected fixed in
go github.com/mattermost/mattermost-server
>=11.6.0, <11.6.1
>=11.5.0, <11.5.5
>=10.11.0, <10.11.17
>=10.11.0+incompatible, <10.11.17+incompatible
>=11.5.0+incompatible, <11.5.5+incompatible
>=11.6.0+incompatible, <11.6.1+incompatible
11.6.1
11.5.5
10.11.17
10.11.17+incompatible
11.5.5+incompatible
11.6.1+incompatible
go github.com/mattermost/mattermost/server/v8
>=8.0.0-20250731163400-5b955468ea1e, <8.0.0-20260501142004-99b73d4c4acf
8.0.0-20260501142004-99b73d4c4acf
go github.com/mattermost/mattermost-server/v5
all versions
 no fix listed
go github.com/mattermost/mattermost-server/v6
all versions
 no fix listed

Affected products

  • Mattermost Mattermost

Classification

Weakness

References

Sources

Fencer Vulns keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.