Key points
- Craft CMS versions 5.0.0 through 5.10.x contain a critical authorization bypass vulnerability.
- The flaw allows site-scoped GraphQL tokens to mutate content on different sites within the same installation.
- Attackers can create, delete, or modify entries, categories, tags, and shared assets using stolen tokens.
An attacker holding a valid GraphQL token for one site can now alter content on entirely different sites within the same Craft CMS installation. This capability arises because the software fails to enforce site isolation checks when processing these tokens. The vulnerability, rated 9.3 critical by the National Vulnerability Database, affects all versions from 5.0.0 up to, but not including, 5.11.0.
In plain English
Craft CMS uses tokens to allow applications or scripts to interact with its content without logging in as a user. These tokens are usually limited to a specific site within a multi-site setup. However, a flaw in the authorization logic means the system does not verify that the token belongs to the site being targeted. Consequently, a token issued for Site A can be used to push changes to Site B.
The background
The issue is tracked as CVE-2026-112776 and is classified under CWE-863, which covers improper authorization checks. The root cause is that the `requireAllowedSite()` function is not enforced during GraphQL mutations. This omission allows an attacker to supply a `siteId` parameter that differs from the one associated with their token, effectively bypassing the intended scope restrictions.
What changes now
Organisations running Craft CMS must verify their version numbers immediately. Any installation running version 5.0.0 or any subsequent release before 5.11.0 is vulnerable. The National Vulnerability Database confirms that the flaw permits the creation of new entries on unintended sites, as well as the deletion of shared assets, tags, and categories.
The attacker's path
Teams usually monitor for anomalous GraphQL activity that targets sites different from the source of the request. Check whether your logging captures the `siteId` parameter alongside token origins to detect scope violations. This stage of an intrusion serves to expand access beyond initial footholds, allowing adversaries to manipulate data across isolated boundaries without needing additional credentials or exploiting further software flaws.
What to do and how to stay safe: Craft CMS
- Audit your Craft CMS version and upgrade to 5.11.0 or later as soon as it is available.
- Review GraphQL logs for requests where the token’s origin site differs from the target `siteId`.
- Rotate any potentially compromised GraphQL tokens immediately to invalidate existing access.
- Restrict network access to GraphQL endpoints to trusted internal services only.
Step-by-step guide: Emergency Patching: Correcting Five Common Operational Errors
General security guidance from the RedTeam Log newsroom. It is not confirmed advice from the organisations named in this story.
Frequently asked questions
Which Craft CMS versions are affected by this vulnerability?
Versions 5.0.0 up to, but not including, 5.11.0 are affected.
What can an attacker do with this flaw?
They can create entries on other sites and delete shared entries, categories, tags, and assets.
Is this vulnerability currently being exploited in the wild?
The source material does not state whether active exploitation has been observed.
