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Fencer Vulns
medium 4.3

CVE-2026-6689 json

*Missing* {{invite_user}} *permission check on team creation allows unprivileged users to set open-invite and allowed-domains team settings*

published 2026-06-12 4 mo ago modified 2026-09-10 1 mo ago also GHSA-c28q-m4gf-vg4q , GO-2026-6283 , EUVD-2026-36501

cvss
4.3
version 3.1, CNA
cisa kev
Not listed
not in CISA's catalog
epss
0.2%
EPSS 0.2% chance of exploitation in 30 days, percentile 4%
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 enforce PermissionInviteUser when setting AllowOpenInvite or AllowedDomains during team creation (the check was only applied on update/patch), which allows an authenticated user holding PermissionCreateTeam but not PermissionInviteUser on the resulting team to configure invite-controlled team settings (make the team publicly joinable via open invite and/or constrain membership via allowed domains) that they are not permitted to set on an existing team via POST /api/v4/teams with allow_open_invite: true and/or a non-empty allowed_domains in the request body.. Mattermost Advisory ID: MMSA-2026-00655

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 8.0.0-20260501144115-7d6816abdfd1
  • 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
partial
Assessed
4 mo ago

Exploit prediction

0.15% chance of exploitation in the next 30 days, higher than 4% of all scored CVEs (FIRST EPSS, 2026-11-08).

CVSS scores

assigned by version score vector
CNA 3.1 4.3 CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:L/A:N
GitHub 3.1 4.3 CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:L/A:N

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, <8.0.0-20260501144115-7d6816abdfd1
8.0.0-20260501144115-7d6816abdfd1
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.