What is CVE-2026-19541?

CVE-2026-19541 is a medium-severity vulnerability in Mattermost, classified under Insertion of Sensitive Information into Sent Data. CVSS score: 6.5/10. Published 2026-10-16.

How severe is CVE-2026-19541?

Medium severity. CVSS v3 base score is 6.5 out of 10.

Vulnerability in Mattermost

CVE-2026-19541

Mattermost versions 11.9.x <= 11.9.1, 11.8.x <= 11.8.5, 11.7.x <= 11.7.10, 11.10.x <= 11.10.1 fail to require re-entry of the stored client secret when validating an outgoing OAuth connection, which allows an authenticated user with permission to manage outgoing OAuth connections to obtain the secret via pointing the token URL at an attacker-controlled endpoint and triggering validation.. Mattermost Advisory ID: MMSA-2026-00761

Published 2026-10-16 · last modified 2026-10-16.

CVSS v3 metric

CVSS v3 base score 6.5 (Medium). Vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:N.

EPSS exploit prediction

No EPSS score from FIRST.org yet. New CVEs usually get one within a few days; no score means no signal yet, not low risk. How EPSS works.

Affected products

Mattermost

Weakness classification (CWE)

CWE-201 — Insertion of Sensitive Information into Sent Data

References

mattermost.com/security-updates (vendor-advisory)

Frequently asked questions

What is CVE-2026-19541?: CVE-2026-19541 is a medium-severity vulnerability in Mattermost, classified under Insertion of Sensitive Information into Sent Data. CVSS score: 6.5/10. Published 2026-10-16.
How severe is CVE-2026-19541?: Medium severity. CVSS v3 base score is 6.5 out of 10.