CVE-2026-95666
Unbounded post ID array in the bulk reactions endpoint allows denial of service
CVSS Score
4.3
EPSS Score
0.0%
EPSS Percentile
0th
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 limit the length of the post ID array accepted by the bulk reactions endpoint which allows an authenticated user to cause excessive database load via a crafted request to {{POST /api/v4/posts/ids/reactions}}.. Mattermost Advisory ID: MMSA-2026-00771
| CWE | CWE-770 |
| Vendor | mattermost |
| Product | mattermost |
| Published | Sep 22, 2026 |
| Last Updated | Sep 22, 2026 |
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CVSS v3 Breakdown
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:L Attack Vector
Network
Attack Complexity
Low
Privileges Required
Low
User Interaction
None
Scope
Unchanged
Confidentiality
None
Integrity
None
Availability
Low
Affected Versions
Mattermost / Mattermost
11.9.0 ≤ 11.9.1 11.8.0 ≤ 11.8.5 11.7.0 ≤ 11.7.10 11.10.0 ≤ 11.10.1
Credits
idr