CVE-2026-16046
Received Received - Intake

Run State Modification in Mattermost Playbook Runs

Publication date: 2026-08-17

Last updated on: 2026-08-17

Assigner: Mattermost, Inc.

Description
Mattermost versions 11.7.x <= 11.7.6, 10.11.x <= 10.11.21 fail to enforce run-state validation on write operations for finished playbook runs which allows a run participant to modify status, checklists, retrospective content, ownership, and participants on completed runs via REST and GraphQL API requests. Mattermost Advisory ID: MMSA-2026-00675

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Meta Information

Published
2026-08-17
Last Modified
2026-08-17
Generated
2026-08-17
AI Q&A
2026-08-17
EPSS Evaluated
N/A
NVD
CVE-2026-16046
EUVD
EUVD-2026-60207

Affected Vendors & Products

Showing 2 associated CPEs
Vendor Product Version / Range
mattermost mattermost to 11.7.6 (inc)
mattermost mattermost to 10.11.21 (inc)

Helpful Resources

Exploitability

CWE
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KEV
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CWE ID Description
CWE-863 The product performs an authorization check when an actor attempts to access a resource or perform an action, but it does not correctly perform the check.

Attack-Flow Graph

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Executive Summary

Mattermost versions between 11.7.0 and 11.7.6, and 10.11.0 and 10.11.21, do not validate if a playbook run is completed before allowing write operations. This lets participants modify details like status, checklists, content, ownership, and participants on already finished runs through REST or GraphQL API requests.

Detection Guidance

To detect this vulnerability, check Mattermost server logs for unauthorized REST or GraphQL API requests modifying completed playbook runs. Look for POST/PUT requests targeting /api/v4/playbooks/runs/{run_id} or /api/graphql with payloads altering status, checklists, or participants after run completion.

Impact Analysis

An attacker with access to a completed playbook run could alter its records, potentially changing ownership, participant lists, or retrospective content. This could lead to incorrect data, misattribution, or unauthorized modifications to sensitive information.

Compliance Impact

This vulnerability could compromise data integrity for compliance records. Modifying completed playbook runs may violate audit trails required by GDPR or HIPAA, leading to non-compliance, potential fines, or loss of certification.

Mitigation Strategies

Upgrade Mattermost to a version that is not affected by this vulnerability. Specifically, upgrade to a version higher than 11.7.6 or 10.11.21 depending on your current installation.

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