CVE-2026-2456
Medium
Description
Mattermost versions 11.3.x <= 11.3.0, 11.2.x <= 11.2.2, 10.11.x <= 10.11.10 Mattermost fails to limit the size of responses from integration action endpoints, which allows an authenticated attacker to cause server memory exhaustion and denial of service via a malicious integration server that returns an arbitrarily large response when a user clicks an interactive message button.. Mattermost Advisory ID: MMSA-2026-00571
SeverityMedium
CVSS5.3
Exploit probability—
Product
Mattermost Server
PublishedMar 16, 2026
First seenMar 16, 2026
Weakness typeCWE-789CWE-789
How to fix
Update
- mattermost mattermost_server10.11.11, 11.2.3, 11.3.1 or later
- github.com/mattermost/mattermost/server/v88.0.0-20260127165411-fe3052073dc6 or later
- github.com/mattermost/mattermost-server5.3.2-0.20260127165411-fe3052073dc6, 10.11.11, 11.2.3, 11.3.1, 10.11.11+incompatible, 11.2.3+incompatible, 11.3.1+incompatible or later
Vendor advisories
Affected products
| Product | Affected versions | Fixed in |
|---|---|---|
| mattermost mattermost_server | 10.11.0 ≤ v < 10.11.11, 11.2.0 ≤ v < 11.2.3, 11.3.0 ≤ v < 11.3.1 | 10.11.11, 11.2.3, 11.3.1 |
| github.com/mattermost/mattermost/server/v8Go | v < 8.0.0-20260127165411-fe3052073dc6 | 8.0.0-20260127165411-fe3052073dc6 |
| github.com/mattermost/mattermost-serverGo | v < 5.3.2-0.20260127165411-fe3052073dc6, 10.11.0-rc1 ≤ v < 10.11.11, 11.2.0-rc1 ≤ v < 11.2.3, 11.3.0-rc1 ≤ v < 11.3.1, 10.11.0-rc1+incompatible ≤ v < 10.11.11+incompatible, 11.2.0-rc1+incompatible ≤ v < 11.2.3+incompatible, 11.3.0-rc1+incompatible ≤ v < 11.3.1+incompatible | 5.3.2-0.20260127165411-fe3052073dc6, 10.11.11, 11.2.3, 11.3.1, 10.11.11+incompatible, 11.2.3+incompatible, 11.3.1+incompatible |
| github.com/mattermost/mattermost-server/v5Go | No range specified | — |
| github.com/mattermost/mattermost-server/v6Go | No range specified | — |
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