Improper post type validation on scheduled post endpoints

CISA KEV is observed exploitation evidence. FIRST EPSS is a dated prediction of exploitation in the next 30 days. Missing scores are unknown. This collector requests predictions only for explicit CVE aliases in the public NuGet archive; Microsoft release views retain their existing prediction scope.

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Mattermost versions 11.7.x <= 11.7.10 fail to validate reserved system post types on the scheduled post creation and publication paths which allows an authenticated channel member to publish messages rendering as trusted system events via the scheduled post endpoint.. Mattermost Advisory ID: MMSA-2026-00732

Source published

26 Oct 2026 14:15:12 UTC

Source modified

26 Oct 2026 14:15:12 UTC

Observed here

26 Oct 2026 15:35:30 UTC

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CVSS 3.1 · 3.5 CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:U/C:N/I:L/A:N