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CVE-2026-2457

4.3 mediumEPSS 0.1%

Medium (4.3) in mattermost mattermost server. EPSS 0.1% chance of exploitation in the next 30 days. Fixed in github.com/mattermost/mattermost/server/v8 8.0.0-20260123211116-9efe617be8b8.

Mattermost versions 11.3.x <= 11.3.0, 11.2.x <= 11.2.2, 10.11.x <= 10.11.10 fail to sanitize client-supplied post metadata which allows an authenticated attacker to spoof permalink embeds impersonating other users via crafted PUT requests to the post update API endpoint.. Mattermost Advisory ID: MMSA-2025-00569

Severity

CVSS 3.1

4.3 medium
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:L/A:N
EPSS
0.1% chance of exploitation in the next 30 days; higher than 1% of CVEs (scores of 2026-10-31)
CWE
CWE-346
Published
Modified
Record from
the NVD, synced

Affected

Packages (OSV)

AdvisoryEcosystemPackageAffectedFixed in
GHSA-ph22-fw5m-w2q9Gogithub.com/mattermost/mattermost/server/v8<8.0.0-20260123211116-9efe617be8b88.0.0-20260123211116-9efe617be8b8
GHSA-ph22-fw5m-w2q9Gogithub.com/mattermost/mattermost-server<5.3.2-0.20260123211116-9efe617be8b85.3.2-0.20260123211116-9efe617be8b8
GHSA-ph22-fw5m-w2q9Gogithub.com/mattermost/mattermost-server>=10.11.0-rc1 <10.11.1110.11.11
GHSA-ph22-fw5m-w2q9Gogithub.com/mattermost/mattermost-server>=11.2.0-rc1 <11.2.311.2.3
GHSA-ph22-fw5m-w2q9Gogithub.com/mattermost/mattermost-server>=11.3.0-rc1 <11.3.111.3.1
GO-2026-4732Gogithub.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 <11.3.1+incompatible		10.11.11+incompatible, 11.2.3+incompatible, 11.3.1+incompatible
GO-2026-4732Gogithub.com/mattermost/mattermost-server/v5all versionsno fix published
GO-2026-4732Gogithub.com/mattermost/mattermost-server/v6all versionsno fix published
GO-2026-4732Gogithub.com/mattermost/mattermost/server/v8<8.0.0-20260123211116-9efe617be8b88.0.0-20260123211116-9efe617be8b8

References

Check your stackJSON