What is CVE-2026-19600?

CVE-2026-19600 is a medium-severity vulnerability in Mattermost, classified under Insertion of Sensitive Information into Log File. CVSS score: 4.5/10. Published 2026-10-16.

How severe is CVE-2026-19600?

Medium severity. CVSS v3 base score is 4.5 out of 10.

Information disclosure in Mattermost

CVE-2026-19600

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 sanitize authentication tokens before writing them to server log entries, which allows an attacker with access to server logs to obtain valid session tokens or OAuth access tokens and impersonate authenticated users via the debug-level Mattermost server log.. Mattermost Advisory ID: MMSA-2026-00763

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

CVSS v3 metric

CVSS v3 base score 4.5 (Medium). Vector: CVSS:3.1/AV:N/AC:L/PR:H/UI:R/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-532 — Insertion of Sensitive Information into Log File

References

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

Frequently asked questions

What is CVE-2026-19600?: CVE-2026-19600 is a medium-severity vulnerability in Mattermost, classified under Insertion of Sensitive Information into Log File. CVSS score: 4.5/10. Published 2026-10-16.
How severe is CVE-2026-19600?: Medium severity. CVSS v3 base score is 4.5 out of 10.