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CVE-2026-3115

4.3 mediumEPSS 0.2%

Mattermost versions 11.2.x <= 11.2.2, 10.11.x <= 10.11.10, 11.4.x <= 11.4.0, 11.3.x <= 11.3.1 fail to apply view restrictions when retrieving group member IDs, which allows authenticated guest users to enumerate user IDs outside their allowed visibility scope via the group retrieval endpoint.. Mattermost Advisory ID: MMSA-2026-00594

Severity

CVSS 3.1

4.3 medium
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:L/I:N/A:N
EPSS
0.2% chance of exploitation in the next 30 days; higher than 15% of CVEs (scores of 2026-10-31)
CWE
CWE-863
Published
Modified
Record from
the NVD, synced

Affected

Packages (OSV)

AdvisoryEcosystemPackageAffectedFixed in
GHSA-mpc7-mm28-f6wqGogithub.com/mattermost/mattermost/server/v8>=11.4.0 <11.4.111.4.1
GHSA-mpc7-mm28-f6wqGogithub.com/mattermost/mattermost/server/v8>=11.3.0-rc1 <11.3.211.3.2
GHSA-mpc7-mm28-f6wqGogithub.com/mattermost/mattermost/server/v8>=11.2.0-rc1 <11.2.311.2.3
GHSA-mpc7-mm28-f6wqGogithub.com/mattermost/mattermost/server/v8>=10.11.0-rc1 <10.11.1110.11.11
GHSA-mpc7-mm28-f6wqGogithub.com/mattermost/mattermost/server/v8>=8.0.0-20260105080200-d27a2195068d <8.0.0-20260217110922-b7d4a1f1f59b8.0.0-20260217110922-b7d4a1f1f59b
GO-2026-5512Gogithub.com/mattermost/mattermost-server>=10.11.0-rc1+incompatible <10.11.11+incompatible
>=11.2.0-rc1+incompatible <11.2.3+incompatible
>=11.3.0-rc1+incompatible <11.3.2+incompatible
>=11.4.0+incompatible <11.4.1+incompatible		10.11.11+incompatible, 11.2.3+incompatible, 11.3.2+incompatible, 11.4.1+incompatible
GO-2026-5512Gogithub.com/mattermost/mattermost-server/v5all versionsno fix published
GO-2026-5512Gogithub.com/mattermost/mattermost-server/v6all versionsno fix published
GO-2026-5512Gogithub.com/mattermost/mattermost/server/v8>=8.0.0-20260105080200-d27a2195068d <8.0.0-20260217110922-b7d4a1f1f59b8.0.0-20260217110922-b7d4a1f1f59b

References

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