Mattermost versions 10.11.x <= 10.11.20, 11.7.x <= 11.7.5 Mattermost fails to remove thread membership records when a user is removed from or leaves… (CVE-2026-9693)
Mattermost versions 10.11.x up to 10.11.20 and 11.7.x up to 11.7.5 fail to remove thread membership records when a user leaves or is removed from a team. This flaw allows a user who was previously removed but later re-invited to the team to access private channel thread root post content and metadata through the team threads API. The vulnerability has a low severity score and does not impact integrity or availability.
AI Analysis
Technical Summary
CVE-2026-9693 describes a vulnerability in Mattermost versions 10.11.x <= 10.11.20 and 11.7.x <= 11.7.5 where thread membership records are not properly removed when a user leaves or is removed from a team. This results in the user, if re-invited, being able to view private channel thread root post content and metadata via the team threads API. The issue relates to improper cleanup of access control data (CWE-459). The CVSS 3.1 base score is 3.5 (low), reflecting limited confidentiality impact and no integrity or availability impact.
Potential Impact
A previously removed user who is later re-invited to a team can view private thread root post content and metadata that should no longer be accessible. This results in limited confidentiality exposure but does not affect data integrity or availability.
Mitigation Recommendations
Patch status is not yet confirmed — check the vendor advisory for current remediation guidance. No official fix or patch links are provided in the available data. Users should monitor Mattermost advisories for updates addressing this issue.
Mattermost versions 10.11.x <= 10.11.20, 11.7.x <= 11.7.5 Mattermost fails to remove thread membership records when a user is removed from or leaves… (CVE-2026-9693)
Description
Mattermost versions 10.11.x up to 10.11.20 and 11.7.x up to 11.7.5 fail to remove thread membership records when a user leaves or is removed from a team. This flaw allows a user who was previously removed but later re-invited to the team to access private channel thread root post content and metadata through the team threads API. The vulnerability has a low severity score and does not impact integrity or availability.
CVSS v3.1
Score 3.5low
Affected software
pkg:github/mattermost/mattermost-serverRun on your own infrastructure? Check whether these packages are installed with threat-finder — our free open-source scanner.
Weaknesses
AI-Powered Analysis
Machine-generated threat intelligence
Technical Analysis
CVE-2026-9693 describes a vulnerability in Mattermost versions 10.11.x <= 10.11.20 and 11.7.x <= 11.7.5 where thread membership records are not properly removed when a user leaves or is removed from a team. This results in the user, if re-invited, being able to view private channel thread root post content and metadata via the team threads API. The issue relates to improper cleanup of access control data (CWE-459). The CVSS 3.1 base score is 3.5 (low), reflecting limited confidentiality impact and no integrity or availability impact.
Potential Impact
A previously removed user who is later re-invited to a team can view private thread root post content and metadata that should no longer be accessible. This results in limited confidentiality exposure but does not affect data integrity or availability.
Mitigation Recommendations
Patch status is not yet confirmed — check the vendor advisory for current remediation guidance. No official fix or patch links are provided in the available data. Users should monitor Mattermost advisories for updates addressing this issue.
Technical Details
- Gcve Source
- db.gcve.eu
- Osv Id
- GHSA-f5mp-j4vf-9jp4
- Osv Schema Version
- 1.4.0
- Aliases
- ["CVE-2026-9693"]
- Ecosystems
- []
- Database Specific Severity
- LOW
- Cvss Version
- 3.1
Threat ID: 6a83aa68bf8831d539e30f25
Added to database: 08/18/2026, 00:42:16 UTC
Last enriched: 08/18/2026, 01:30:50 UTC
Last updated: 08/18/2026, 02:01:18 UTC
Views: 4
Community Reviews
0 reviewsCrowdsource mitigation strategies, share intel context, and vote on the most helpful responses. Sign in to add your voice and help keep defenders ahead.
Want to contribute mitigation steps or threat intel context? Sign in or create an account to join the community discussion.
Actions
Updates to AI analysis require Pro Console access. Upgrade inside Console → Billing.
Need more coverage?
Upgrade to Pro Console for AI refresh and higher limits.
For incident response and remediation, OffSeq services can help resolve threats faster.
Latest Threats
Check if your credentials are on the dark web
Instant breach scanning across billions of leaked records. Free tier available.