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

No CVSS v4.0

Attack Vector Network

Attack Complexity Low

Privileges Required High

Scope Unchanged

Confidentiality Impact High

Integrity Impact None

Availability Impact None

User Interaction Required

No CVSS v3.0

No CVSS v2

This CVE is not in the KEV list.

The EPSS score is 0.00236.

Exploitation none

Automatable no

Technical Impact partial

Default status is the baseline for the product, each version can override it (e.g. patched versions marked unaffected).

Vendor Product Default status Versions
Mattermost Mattermost unaffected
Version Status Constraints
11.9.0 affected ≤ 11.9.1
11.8.0 affected ≤ 11.8.5
11.7.0 affected ≤ 11.7.10
11.10.0 affected ≤ 11.10.1
11.11.0 unaffected —
11.9.2 unaffected —
11.8.6 unaffected —
11.7.11 unaffected —
11.10.2 unaffected —

No data.

No data.

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No data.

Project Subscriptions

No data.

Advisories

No advisories yet.

Fixes

Solution

Update Mattermost to versions 11.11.0, 11.9.2, 11.8.6, 11.7.11, 11.10.2 or higher.

Workaround

No workaround given by the vendor.

References
Link Providers
https://mattermost.com/security-updates cve-icon cve-icon
History

Fri, 16 Oct 2026 13:30:00 +0000

Type Values Removed Values Added
Metrics ssvc

{'options': {'Automatable': 'no', 'Exploitation': 'none', 'Technical Impact': 'partial'}, 'version': '2.0.3'}

Fri, 16 Oct 2026 07:30:00 +0000

Type Values Removed Values Added
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
Title Mattermost logs plaintext authentication tokens in debug-level server logs on failed auth attempts
Weaknesses CWE-532
References
Metrics cvssV3_1

{'score': 4.5, 'vector': 'CVSS:3.1/AV:N/AC:L/PR:H/UI:R/S:U/C:H/I:N/A:N'}

Projects

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cve-icon MITRE

Status: PUBLISHED

Assigner: Mattermost

Published:

Updated: 2026-10-16T12:02:51.761Z

Reserved: 2026-08-12T07:12:44.545Z

Link: CVE-2026-19600

cve-icon Vulnrichment

Updated: 2026-10-16T12:02:45.774Z

cve-icon NVD

Status : Received

Published: 2026-10-16T08:17:13.283

Modified: 2026-10-16T13:16:56.847

Link: CVE-2026-19600

cve-icon Redhat

No data.

cve-icon OpenCVE Enrichment

Updated: 2026-10-16T13:23:41Z

Weaknesses