CVE-2026-79990: GQL entry mutation `siteId` bypasses schema site scope, enabling cross-site content read/write/delete
Craft CMS GraphQL entry mutation resolvers (saveEntry, deleteEntry) read siteIddirectly from$argumentswithout passing throughArgumentManagerprepareArguments(), which is the function that enforces site-scope filtering via arrayintersect 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 Software
Remediation
Recommended actions to resolve this vulnerability, in priority order.
- Configuration
Update the GraphQL entry mutation resolvers (saveEntry, deleteEntry) to obtain site scope from arguments through ArgumentManager::prepareArguments() (the function that enforces site-scope filtering via array_intersect against the GraphQL schema’s allowed sites), instead of reading siteId directly from the $arguments.
Craft CMS GraphQL (entry mutations: saveEntry, deleteEntry) siteId argument handling (bypass of ArgumentManager::prepareArguments) = Use ArgumentManager prepareArguments() for mutation arguments so site-scope filtering via array_intersect is enforced
Event History
Frequently Asked Questions
What level of access does an attacker need?
The attacker needs a GraphQL token scoped to one site, such as Site A. They can then supply another site’s ID in mutation arguments to act on entries in that other site.
Are GraphQL queries subject to the same bypass?
No. The query path calls the argument-preparation function that enforces the schema’s allowed-site filtering, so queries for unauthorized sites return empty results.