CVE-2026-19076

medium

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 swit…

Vendor / product: Mattermost — mattermost server

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

4.9

4.9 (CVSS v3.1)

CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:U/C:N/I:H/A:N

Severity source: NVD CVSS v3.1 (nvd@nist.gov)

Timeline (UTC)

Published: 2026-10-16 08:17

Modified: 2026-10-27 20:57

NVD status: Analyzed

Last synced 20 hours ago

Verified against the source API 2026-10-28 11:30 UTC

Exploitation

Not listed in CISA KEV (as of last catalog sync)

Absence from KEV does not mean a CVE is not exploited. Exploitation status: unknown (no authoritative evidence in our sources).

Affected products

mattermost / mattermost_server ≥11.7.0 <11.7.10, ≥11.8.0 <11.8.6, ≥11.9.0 <11.9.2, 11.10.0

Weakness classification (CWE)

CWE-863

Source: NVD / CISA. “NVD-CWE-Other” and “NVD-CWE-noinfo” mean NVD could not assign a specific weakness.

Mitigation & advisories

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

References

https://mattermost.com/security-updates responsibledisclosure@mattermost.com

Data sources

NVD CVE API 2.0 — fetched 2026-10-28 11:30 UTC · record ↗

Learn the basics

Understanding CVEs and CVSS Scores

CVE-2026-19076

Affected products

Weakness classification (CWE)

Mitigation & advisories

References

Data sources

Learn the basics

Related CVEs