Medium severity · published Oct 16, 2026
CVE-2026-19600
Mattermost logs plaintext authentication tokens in debug-level server logs on failed auth attempts
4.9
CVSS
0.2%
EPSS
No
On KEV
Description
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
CVSS vector
CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:U/C:H/I:N/A:N
Attack vector
Network
Complexity
Low
Privileges
High
User interaction
None
Confidentiality
High
Integrity
None
Availability
None
Scope
Unchanged
Exploitation
Is it being used?
Exploit prediction (EPSS)0.2% · higher than 15% of CVEs
Exploited in the wildNo evidence yet
CISA KEVNot listed
Ransomware campaign useNot known
Affected products
Which versions
MA
Mattermost · Mattermost
11.9.0 through 11.9.1; 11.8.0 through 11.8.5; 11.7.0 through 11.7.10; 11.10.0 through 11.10.1 · source: vendor
MS
Mattermost Server · Mattermost
11.7.0 before 11.7.10; 11.8.0 before 11.8.6; 11.9.0 before 11.9.2; 11.10.0 before 11.10.2 · source: NVD
References
NVD
https://nvd.nist.gov/vuln/detail/CVE-2026-19600
CVE.org
https://www.cve.org/CVERecord?id=CVE-2026-19600
mattermost.com
https://mattermost.com/security-updates
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