Vulnerability · Published May 18, 2026 · Assigned by Mattermost
CVE-2026-2325Improper Input Validation in MS Teams Meetings API Handler
Medium 4.3
In plain English
A medium-severity resource allocation without limits in Mattermost from Mattermost. There are no confirmed reports of exploitation so far. The chance it is exploited in the next 30 days is estimated at 0.2% (higher than 15% of all known vulnerabilities). Fixed versions are available - upgrade the affected package.
Official description
Mattermost versions 11.5.x <= 11.5.1, 10.11.x <= 10.11.13, 11.4.x <= 11.4.3 fail to limit the size of the request body on the start meeting API endpoint, which allows an authenticated attacker to cause resource exhaustion or denial of service via a crafted oversized HTTP POST request to {{/api/v1/meetings}}.. Mattermost Advisory ID: MMSA-2026-00608
Affected packages & fixed versions
| Ecosystem | Package | Fixed in | Advisory |
|---|---|---|---|
| Go | github.com/mattermost/mattermost-plugin-msteams-meetings | 1.1.1-0.20260213105619-c5892dd169de | GHSA-m3p3-8frq-q7qh |
| Go | github.com/mattermost/mattermost-plugin-msteams-meetings | 1.1.1-0.20260213105619-c5892dd169de | GO-2026-5489 |
| Go | github.com/mattermost/mattermost-server | 11.5.2 | GHSA-m3p3-8frq-q7qh |
| Go | github.com/mattermost/mattermost-server | 10.11.14 | GHSA-m3p3-8frq-q7qh |
| Go | github.com/mattermost/mattermost-server | 11.4.4 | GHSA-m3p3-8frq-q7qh |
| Go | github.com/mattermost/mattermost-server | 10.11.14+incompatible, 11.4.4+incompatible, 11.5.2+incompatible | GO-2026-5489 |
Affected products (as reported)
| Vendor | Product | Versions |
|---|---|---|
| Mattermost | Mattermost | 11.5.0 – through 11.5.110.11.0 – through 10.11.1311.4.0 – through 11.4.3 |
Weakness: CWE-770 · Vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:L
References
- MMSA-2026-00608 vendor-advisory