Mattermost versions 10.11.x <= 10.11.12 fail to validate whether users were correctly owned by the correct Connected Workspace which allows a malicious remote server connected using the Conntexted Workspaces feature to change the displayed status of local users via the Connected Workspaces API.. Mattermost Advisory ID: MMSA-2026-00603
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 |
|
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Project Subscriptions
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Advisories
No advisories yet.
Fixes
Solution
Update Mattermost to versions 11.5.0, 10.11.13 or higher.
Workaround
No workaround given by the vendor.
References
| Link | Providers |
|---|---|
| https://mattermost.com/security-updates |
|
History
Wed, 15 Apr 2026 10:45:00 +0000
| Type | Values Removed | Values Added |
|---|---|---|
| Description | Mattermost versions 10.11.x <= 10.11.12 fail to validate whether users were correctly owned by the correct Connected Workspace which allows a malicious remote server connected using the Conntexted Workspaces feature to change the displayed status of local users via the Connected Workspaces API.. Mattermost Advisory ID: MMSA-2026-00603 | |
| Title | Connected Workspaces: Malicious remote server can manipulate arbitrary user's status | |
| Weaknesses | CWE-862 | |
| References |
| |
| Metrics |
cvssV3_1
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Projects
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MITRE
Status: PUBLISHED
Assigner: Mattermost
Published:
Updated: 2026-04-15T10:11:07.676Z
Reserved: 2026-03-16T08:51:03.250Z
Link: CVE-2026-27769
Vulnrichment
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NVD
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Redhat
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OpenCVE Enrichment
No data.
Weaknesses