CVE-2026-57997: Strapi users-permissions - JWT Algorithm Confusion via Missing Algorithm Configuration

Severity: medium (CVSS 5.4 v3.1)
Exploited in the wild: not listed in CISA KEV
EPSS: 0.2% probability of exploitation in the next 30 days
Public exploit or detection template: none known
Published: 2026-06-29 · updated 2026-10-25
Weakness: CWE-327

Description

Strapi users-permissions plugin fails to restrict JWT algorithms when plugin::users-permissions.jwt.algorithm is not explicitly configured, allowing acceptance of HS384 and HS512 tokens alongside HS256. Attackers possessing the jwtSecret can mint tokens with non-standard HMAC variants to bypass algorithm restrictions and weaken authentication controls.

Affected products

strapi: before 5.7.0 — fixed in 5.7.0

How to fix

Upgrade to a fixed version: strapi 5.7.0. Check the vendor advisory for mitigations.

References

https://github.com/strapi/strapi
https://github.com/strapi/strapi/issues/26587
https://github.com/strapi/strapi/pull/26752
https://www.vulncheck.com/advisories/strapi-users-permissions-jwt-algorithm-confusion-via-missing-algorithm-configuration

Get alerted when CVE-2026-57997 or the next vulnerability affects your stack