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Go/github.com/mattermost/mattermost-server CVE-2026-27656: medium 6.1, EPSS 0.18%

Mattermost allows attackers to take over arbitrary user accounts via overly permissive substring matching flaw in github.com/mattermost/mattermost-server

Action: Upgrade github.com/mattermost/mattermost-server to 10.11.12+incompatible or later.

go get github.com/mattermost/mattermost-server@v10.11.12+incompatible
go get github.com/mattermost/mattermost-server@v11.2.4+incompatible
go get github.com/mattermost/mattermost-server@v11.3.2+incompatible
go get github.com/mattermost/mattermost-server@v11.4.1+incompatible

Affected

introducedfixedlast affected
10.11.0-rc1+incompatible10.11.12+incompatible-
11.2.0-rc1+incompatible11.2.4+incompatible-
11.3.0-rc1+incompatible11.3.2+incompatible-
11.4.0-rc1+incompatible11.4.1+incompatible-

Fixed versions

10.11.12+incompatible11.2.4+incompatible11.3.2+incompatible11.4.1+incompatible

Sources

CVE-2026-27656 · published · modified · JSON