CVE-2026-79991: Craft CMS CMS

High severity, CVSS 7.1. EPSS: 0.5% chance of exploitation in the next 30 days.

Craft CMS GraphQL entry mutation resolvers (saveEntry, deleteEntry) read siteIddirectly from$argumentswithout passing throughArgumentManagerprepareArguments(), which is the function that enforces site-scope filtering via array_intersect against the GraphQL schema’s allowed sites. The query path (ElementResolverprepareElementQuery) correctly calls prepareArguments()`, so queries to unauthorized sites return empty. But mutations bypass this entirely — an attacker with a token scoped to Site A can create, modify, or delete entries in Site B by passing siteId in the mutations argument.

Affected products

• Craft CMS CMS: from 5.0.0-RC1, before 5.10.13 (fixed in 5.10.13)

Published 2026-09-02. Last modified 2026-09-03.