Missing authorization check in AI message rewrite endpoint allows access to private thread content
Default status is the baseline for the product, each version can override it (e.g. patched versions marked unaffected).
| Vendor | Product | Default status | Versions | ||||||||||||
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| Mattermost | Mattermost | unaffected |
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No data.
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| Mattermost | Mattermost |
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Vendor Solution
Update Mattermost to versions 11.6.0, 11.5.2 or higher.
| Source | ID | Title |
|---|---|---|
Github GHSA |
GHSA-8r89-8w26-cq32 | Mattermost doesn't verify channel membership when processing AI-assisted message rewrites |
No CVSS v4.0
No CVSS v3.0
No CVSS v2
This CVE is not in the KEV list.
Exploit prediction score: < 1% (0.205% probability within 30 days)
| Link | Providers |
|---|---|
| https://mattermost.com/security-updates |
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| Type | Values Removed | Values Added |
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| First Time appeared |
Mattermost mattermost Server
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| CPEs | cpe:2.3:a:mattermost:mattermost_server:*:*:*:*:*:*:*:* | |
| Vendors & Products |
Mattermost mattermost Server
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| Type | Values Removed | Values Added |
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| Metrics |
ssvc
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| Type | Values Removed | Values Added |
|---|---|---|
| First Time appeared |
Mattermost
Mattermost mattermost |
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| Vendors & Products |
Mattermost
Mattermost mattermost |
| Type | Values Removed | Values Added |
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| Description | Mattermost versions 11.5.x <= 11.5.1 fail to verify channel membership when processing AI-assisted message rewrites which allows an authenticated attacker to read the content of threads in private channels and direct messages they do not have access to via a crafted request to the post rewrite endpoint.. Mattermost Advisory ID: MMSA-2026-00645 | |
| Title | Missing authorization check in AI message rewrite endpoint allows access to private thread content | |
| Weaknesses | CWE-862 | |
| References |
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| Metrics |
cvssV3_1
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