Authentication Token Exposure in Mattermost by Mattermost
CVE-2026-19600

4.5MEDIUM

Key Information:

Vendor

Mattermost
Status
Mattermost
Vendor
CVE Published:
16 October 2026

What is CVE-2026-19600?

Certain versions of Mattermost exhibit a vulnerability that fails to properly sanitize authentication tokens in server log entries. This oversight can permit malicious actors with access to the server logs to extract valid session tokens or OAuth access tokens, potentially enabling them to impersonate legitimate users. It is critical for administrators to review server logging practices and ensure they are adhering to security best practices to mitigate this risk.

Affected Version(s)

Mattermost 11.9.0 <= 11.9.1

Mattermost 11.8.0 <= 11.8.5

Mattermost 11.7.0 <= 11.7.10

References

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

CVSS V3.1

Score:
4.5
Severity:
MEDIUM
Confidentiality:
High
Integrity:
None
Availability:
High
Attack Vector:
Network
Attack Complexity:
Low
Privileges Required:
High
User Interaction:
Required
Scope:
Unchanged

Timeline

  • Vulnerability published

  • Vulnerability Reserved

Credit

CERT PL
.