CVE-2026-17153

This CVE exposes a flaw in how the plugin scoped its AJAX endpoint's nonce: the sg_ai_studio_gutenberg_nonce was issued to every user with block editor access, which includes Contributors who lack the upload_files capability. The endpoint correctly verified the nonce for CSRF protection but never performed the capability check that should gate the actual action. The result is an authorization bypass where authenticated Contributors can upload arbitrary files to the media library. The critical misunderstanding here is treating nonce verification as sufficient authorization. Nonces prove a user initiated a request within their session — they don't prove the user has permission to perform the specific action. WordPress's role-based capability system exists precisely because nonces can't express "this user can do X but not Y." The plugin emitted the nonce to all block editor users, then trusted that token as authorization rather than layering on the capability check that would actually enforce the boundary. Two things defenders should check: first, whether any AJAX endpoints in your plugins verify a nonce but skip current_user_can() checks — grep for wp_verify_nonce calls that aren't followed by capability verification; second, examine who receives nonces in your admin area and whether that emission scope aligns with what those endpoints actually do. The nonce emission scope is a configuration decision that has security implications downstream. The CVSS 5.3 score is misleading. This requires Contributor-level access — the lowest privilege tier that can authenticate — and rewards exploitation with persistent file storage. In practice, that's a high-value, low-barrier payload that the base score doesn't adequately capture. Treat this as a medium-severity technical finding but high-severity operational risk.

Reviewed through automated stages and approved by a human before publication.