HIGH 8.8 NVD
CVE-2026-54239
Faust.js is a headless WordPress toolkit. Prior to 1.8.11, the FaustWP WordPress plugin authenticates only the ciphertext in its token envelope and excludes the
Faust.js is a headless WordPress toolkit. Prior to 1.8.11, the FaustWP WordPress plugin authenticates only the ciphertext in its token envelope and excludes the 16-byte initialization vector from the HMAC in WPE\FaustWP\Auth\encrypt() and WPE\FaustWP\Auth\decrypt() in plugins/faustwp/includes/auth/functions.php. A logged-in non-administrator who obtains an authorization code from GET /generate can modify the unauthenticated initialization vector so that CBC decryption changes the token type and user identifier while the HMAC remains valid. This can produce an access token for an Administrator and permit full WordPress REST API access, administrator-account creation, plugin installation, and arbitrary code execution. This issue is fixed in repository version 1.8.11.
References
- https://github.com/wpengine/faustjs/commit/cda00de7290f9b178cb1652d30b4cdf5bb8688d0
- https://github.com/wpengine/faustjs/pull/2386
- https://github.com/wpengine/faustjs/security/advisories/GHSA-q6pm-r77q-qcv3
This high severity vulnerability with a CVSS score of 8.8 was published on 2026-09-17 via NVD.
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