CVE-2026-19076: Mattermost · Incorrect Authorization
Affects MattermostSource GCVE Database
Not known to be exploited · CVSS 4.4 Medium.
Data as of 27 Oct 2026, 22:42 UTC
CVSS:3.1/AV:N/AC:H/PR:H/UI:N/S:U/C:N/I:H/A:NExploitation evidence
Disclosed: evidence found.
CVE published 16 Oct 2026
Detectable: no evidence on record.
No public nuclei template indexed
Weaponised: no evidence on record.
No public exploit code indexed in Metasploit or Exploit-DB
Exploited in the wildExploited: no evidence on record.
Not in CISA KEV and no source reports exploitation
Observed by OffSeq MirageSeen by Mirage: no evidence on record.
No attack traffic recorded by OffSeq Mirage sensors
A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), the Metasploit, Exploit-DB and nuclei-templates index as of 26 Oct 2026.
What to do
Affected software
| Product | Affected | Fixed in |
|---|---|---|
| Mattermost Mattermost | Affected
| Fixed in– |
AI-suggested
Until a fix is available, restrict OAuth bearer token distribution and monitor for suspicious activity involving the /api/v4/users/login/switch endpoint.
Description
CVE-2026-19076 is an incorrect authorization vulnerability in Mattermost affecting certain 11.x versions. It allows an attacker with a valid OAuth bearer token for a target user to permanently take over that user's SSO-backed account by exploiting the account type switch endpoint. The attacker can set a password and detach the account from its identity provider via a crafted POST request to /api/v4/users/login/switch. This vulnerability impacts Mattermost versions 11.10.0, 11.7.0, 11.9.0, and 11.8.0.