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Go/github.com/mattermost/mattermost-server CVE-2026-5740: unknown, EPSS 0.57%

Mattermost doesn't properly validate msgpack-encoded WebSocket frames before memory allocation in github.com/mattermost/mattermost-server

Action: Upgrade github.com/mattermost/mattermost-server to 10.11.15+incompatible or later.

go get github.com/mattermost/mattermost-server@v10.11.15+incompatible
go get github.com/mattermost/mattermost-server@v11.4.5+incompatible
go get github.com/mattermost/mattermost-server@v11.5.4+incompatible
go get github.com/mattermost/mattermost-server@v11.6.1+incompatible

Affected

introducedfixedlast affected
10.11.0+incompatible10.11.15+incompatible-
11.4.0+incompatible11.4.5+incompatible-
11.5.0+incompatible11.5.4+incompatible-
11.6.0+incompatible11.6.1+incompatible-

Fixed versions

10.11.15+incompatible11.4.5+incompatible11.5.4+incompatible11.6.1+incompatible

Sources

CVE-2026-5740 · published · modified · JSON