Medium 4.4Published Oct 16, 2026

CVE-2026-19076Mattermost fails to reject OAuth application sessions in account type switch, allowing account takeover via bearer token

Updated under an hour ago (Oct 28, 2026, 7:10 AM ET)

Does this affect you?

It affects Mattermost and 1 other product. Add what you run to find out whether that includes you.

No exploitation reported and no EPSS estimate yet.

Do this next

Start free and add your stack

Free account, 1 product

Every CVE for Mattermost

Exploited in the last 30 days

Mattermost versions 11.10.x <= 11.10.0, 11.7.x <= 11.7.9, 11.9.x <= 11.9.1, 11.8.x <= 11.8.5 fail to reject OAuth application sessions in the account type switch endpoint, which allows an attacker with a valid OAuth bearer token for a target user to permanently take over that user's SSO-backed account by setting an attacker-controlled password and detaching the account from its identity provider via a crafted request to POST /api/v4/users/login/switch.. Mattermost Advisory ID: MMSA-2026-00758

CVSS: 4.4 MEDIUM (v3.1, CNA)CVSS:3.1/AV:N/AC:H/PR:H/UI:N/S:U/C:N/I:H/A:N
Weakness (CWE): CWE-863
Known exploited: Not in CISA's KEV catalog
EPSS (exploitation in the next 30 days): Not loaded for this CVE
Assigned by: Mattermost
NVD analysis: Analyzed
Record last updated: Oct 16, 2026
First seen by InfoSec Signals: Oct 16, 2026

Affected products

Affected products

Mattermost Mattermost mattermost:mattermost (from the name)	from 11.10.0 through 11.10.0; from 11.7.0 through 11.7.9; from 11.9.0 through 11.9.1; from 11.8.0 through 11.8.5; 11.11.0 not affected; 11.10.1 not affected; 11.7.10 not affected; 11.9.2 not affected; and 1 more ranges	CNA record
mattermost mattermost_server mattermost:mattermost_server	from 11.7.0 before 11.7.10; from 11.8.0 before 11.8.6; from 11.9.0 before 11.9.2; 11.10.0	NVD

References

References

https://mattermost.com/security-updates	vendor-advisory

The CVE record on cve.org NVD's entry

The CVE record is authoritative. Products marked “from the name” were identified from the CNA's free-text names, not a CPE, and are matched less certainly. This product uses the NVD API but is not endorsed or certified by the NVD.