CVE-2026-27886: Strapi may leak sensitive data via relational filtering due to lack of query sanitization
Summary of CVE-2026-27886 Vulnerability Details
- CVE: CVE-2026-27886 - CVSS v3.1 Vector: CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:N/VA:N/SC:H/SI:N/SA:N (9.3 — Critical) - Affected Versions: @strapi/strapi <=5.36.1 - How to Patch: Immediately update your Strapi to >=5.37.0
Description of CVE-2026-27886
Strapi versions prior to 5.37.0 did not sufficiently sanitize query parameters when filtering content via relational fields. An unauthenticated attacker could use the where query parameter on any publicly-accessible content-type with an updatedBy (or other admin-relation) field to perform a boolean-oracle attack against private fields on the joined adminusers table, including the resetPasswordToken field. Extracting an admin reset token via this oracle made full administrative account takeover possible without authentication.
When a filter such as where[updatedBy][resetPasswordToken][$startsWith]=a was applied to a public Content API endpoint, the underlying query generation performed a LEFT JOIN against the adminusers table and emitted a WHERE clause referencing the joined column. The query parameter sanitization layer did not block operator chains that traversed into relational target schemas the caller had no read permission on, allowing the response count to be used as a one-bit oracle on any admin-table field.
The patch introduces explicit query-parameter sanitization at the controller and service boundary via three new primitives: strictParam, addQueryParams, and addBodyParams. Operator chains that traverse into restricted relational targets are now rejected before reaching the database.
IoC's for CVE-2026-27886
Indicators that an instance running an unpatched version may have been exploited:
- Server access logs containing query strings traversing into admin-relation private fields. Regex: \?(.&)?where\[(updatedBy|createdBy|publishedBy)\]\[(email|password|resetPasswordToken|confirmationToken|firstname|lastname|preferedLanguage)\]\[\$(startsWith|contains|eq|gt|lt|ge|le|in|notIn|notNull|null)\]= - High volume of public Content API requests from a single IP iterating through a hex alphabet (0-9, a-f) on the same content-type endpoint with progressively-longer filter values - Subsequent POST /admin/reset-password calls using a reset token that the legitimate admin did not request - Successful admin password change immediately following a burst of public Content API requests with where[updatedBy] query parameters - Sustained burst of identical-shape requests with only the trailing character of the filter value varying
Credit Discovered by: James Doll - WildWest CyberSecurity Contact: cve+2026-27886@wildwestcyber.com Website: https://wildwestcyber.com LinkedIn: https://www.linkedin.com/in/james-doll-273a61243
Other sources
Strapi is an open source headless content management system. Strapi versions starting in 4.0.0 and prior to 5.37.0 did not sufficiently sanitize query parameters when filtering content via relational fields. An unauthenticated attacker could use the where query parameter on any publicly-accessible content-type with an updatedBy (or other admin-relation) field to perform a boolean-oracle attack against private fields on the joined adminusers table, including the resetPasswordToken field. Extracting an admin reset token via this oracle made full administrative account takeover possible without authentication. When a filter such as where[updatedBy][resetPasswordToken][$startsWith]=a was applied to a public Content API endpoint, the underlying query generation performed a LEFT JOIN against the adminusers table and emitted a WHERE clause referencing the joined column. The query parameter sanitization layer did not block operator chains that traversed into relational target schemas the caller had no read permission on, allowing the response count to be used as a one-bit oracle on any admin-table field. The patch in version 5.37.0 introduces explicit query-parameter sanitization at the controller and service boundary via three new primitives: strictParam, addQueryParams, and addBodyParams. Operator chains that traverse into restricted relational targets are now rejected before reaching the database.
— MITRE
Affected Software
Event History
Frequently Asked Questions
What is the severity of CVE-2026-27886?
CVE-2026-27886 has a CVSS score of 9.3, indicating it is critical in severity.
How do I fix CVE-2026-27886?
To fix CVE-2026-27886, you must update your Strapi to version 5.37.0 or later.
What versions are affected by CVE-2026-27886?
CVE-2026-27886 affects versions of @strapi/strapi up to and including 5.36.1.
What kind of vulnerability is CVE-2026-27886?
CVE-2026-27886 is categorized as a critical security vulnerability affecting the Strapi framework.
Is there a workaround for CVE-2026-27886?
There are no known workarounds for CVE-2026-27886; updating to the latest version is the only solution.