Mattermost versions 11.5.x <= 11.5.1, 10.11.x <= 10.11.13, 11.4.x <= 11.4.3 fail to validate that a remote cluster has access to a channel before processing membership removal requests during shared channel membership sync, which allows a malicious remote cluster to remove any user from any channel, including private channels, via crafted membership sync messages targeting channels the remote cluster is not authorized to access. Mattermost Advisory ID: MMSA-2026-00576
Mattermost versions 11.5.x <= 11.5.1, 10.11.x <= 10.11.13, 11.4.x <= 11.4.3 fail to validate that a remote cluster has access to a channel before processing membership removal requests during shared channel membership sync, which allows a malicious remote cluster to remove any user from any channel, including private channels, via crafted membership sync messages targeting channels the remote cluster is not authorized to access. Mattermost Advisory ID: MMSA-2026-00576
왜 이 VPI인가 (설명가능 · 실험적)
VPI 산정 기준
| 영향도 | 43.00 |
| 악용 신호(추가 악용신호 없음) | ×1.00 |
| VPI | 43.00 |
VPI 공식 vpi-v1 기준
| 소스 | CVSS 버전 | 기본 점수 | 심각도 | 벡터 문자열 | 평가일 |
|---|---|---|---|---|---|
| OSV3rd | 3.1 | 4.3 | MEDIUM | CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:L/A:N | 2026. 06. 26. |
| NVDNIST | 3.1 | 4.3 |
| CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:L/A:N |
| 2026. 05. 18. |