CVE-2026-6673

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CVSS 3.1

6.4 medium

EPSS

<1%p22

Published

Jun 22, 2026 (Jun 22, 2026)

Modified

Sep 15, 2026

Description

Mattermost versions 11.7.x <= 11.7.0, 11.6.x <= 11.6.2, 11.5.x <= 11.5.5, 10.11.x <= 10.11.17 fail to authenticate Atlassian Connect installed callbacks, allowing a remote unauthenticated attacker to inject a rogue sharedSecret and disrupt the Jira integration via POST to /ac/installed during the pending-install window.. Mattermost Advisory ID: MMSA-2026-00654

Vendors: mattermost
Products: mattermost server
Ecosystems: go
Weakness: CWE-306
Vector: CVSS:3.1/AV:N/AC:H/PR:L/UI:R/S:U/C:N/I:H/A:H
GHSA: GHSA-jqgv-39mg-7c2r (medium)

NVD CVE.org GitHub PoCs EPSS (0.3%)

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