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CVE-2026-3433

Mattermost fails to scope role_updated websocket events to authorized team and channel members

CVSS 3.1 4.3 MEDIUMEUVD CVSS 3.1 4.3 CVSS 3.1 · [email protected] · Secondary 4.3 MEDIUMCVSS_V3 Publisher rating MODERATEFixed by github.com/mattermost/mattermost-server 11.6.1Fixed by github.com/mattermost/mattermost-server 11.5.5Fixed by github.com/mattermost/mattermost-server 10.11.17Fixed by github.com/mattermost/mattermost/server/v8 8.0.0-20260504071740-9408b98025d7osv · severity unknownFixed by github.com/mattermost/mattermost-server 10.11.17+incompatibleFixed by github.com/mattermost/mattermost-server 11.5.5+incompatibleFixed by github.com/mattermost/mattermost-server 11.6.1+incompatibleFixed by github.com/mattermost/mattermost/server/v8 8.0.0-20260504071740-9408b98025d7KEV status unknown
Original advisory

cve-program · CVE-2026-3433

Published

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 restrict role_updated websocket event broadcasts to members of the affected team or channel which allows an authenticated attacker with guest-level access to observe permission scheme change notifications for private teams they are not a member of via the websocket connection.. Mattermost Advisory ID: MMSA-2026-00616

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euvd · EUVD-2026-36498

Published

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 restrict role_updated websocket event broadcasts to members of the affected team or channel which allows an authenticated attacker with guest-level access to observe permission scheme change notifications for private teams they are not a member of via the websocket connection.. Mattermost Advisory ID: MMSA-2026-00616

Read the publisher's advisory

nvd · CVE-2026-3433

Published

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 restrict role_updated websocket event broadcasts to members of the affected team or channel which allows an authenticated attacker with guest-level access to observe permission scheme change notifications for private teams they are not a member of via the websocket connection.. Mattermost Advisory ID: MMSA-2026-00616

Read the publisher's advisory

osv · GHSA-rp4v-qc77-phm4

Published

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 restrict role_updated websocket event broadcasts to members of the affected team or channel, which allows an authenticated attacker with guest-level access to observe permission scheme change notifications for private teams they are not a member of via the websocket connection. Mattermost Advisory ID: MMSA-2026-00616

Read the publisher's advisory

osv · GO-2026-6286

Published

Mattermost doesn't restrict role_updated websocket event broadcasts to members of the affected team or channel in github.com/mattermost/mattermost-server

Read the publisher's advisory

Affected versions, risk and source history

Related advisories and sources

Publishers link these advisories through the identifiers shown below. A shared identifier or date alone does not tell you whether your software is affected or whether the advisories describe the same cause.

CVE-2026-3433 · CVE overview and exploitation status

EUVD-2026-36498

GHSA-rp4v-qc77-phm4

GO-2026-6286

cve-program · CVE-2026-3433

euvd · EUVD-2026-36498

nvd · CVE-2026-3433

osv · GHSA-rp4v-qc77-phm4

osv · GO-2026-6286

Related changes

Linked by CVE identifier
ChangeIntel

An IT change radar: releases, security, known issues, retirements, documentation changes, and service status from public sources. Every item links to supporting evidence; dates and statuses can change after they are read.

Sources read 15 Nov 13:16 UTC · 255 of 275 readable · 250 fully read · documentation 469/469 current

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