CVE-2026-104803
Vulnérabilité critique dans WPCOM Member (whyun)
Description
The WPCOM Member plugin for WordPress is vulnerable to Authentication Bypass in all versions up to, and including, 1.7.27 via the `uuid` and `code` parameters of the social-login callback handler registered on the `init` hook. The vulnerability exists because the `login` function's social-login flow performs no nonce validation, no OAuth state verification, and no per-visitor namespace isolation in the session store, allowing an unauthenticated attacker to issue a crafted GET request that writes an attacker-named, attacker-valued entry into the global session namespace (bypassing the per-visitor prefix by prepending an underscore), then issue a second GET request triggering `weapp_new_user()` to read that forged entry and resolve the attacker-supplied `openid` value to a bound WordPress account before `wp_set_auth_cookie()` establishes a fully authenticated session. This makes it possible for unauthenticated attackers to log in as any WordPress user — including administrators — whose bound social provider identifier (openid/unionid) is known or discoverable. Successful exploitation requires that the target site has at least one social provider configured (which activates the vulnerable handler) and that the attacker knows or can enumerate the victim account's bound openid or unionid.
Gravité et risque d'exploitation
CVE-2026-104803 obtient un score CVSS de 9.8/10, soit une gravité critique. Selon le modèle EPSS, la probabilité qu'elle soit exploitée dans les 30 prochains jours est de 0.45 %, ce qui la place devant 37.7 % des CVE référencées.
Que faire ?
- Vérifiez si WPCOM Member (versions <=1.7.27, 0) est présent sur votre parc.
- Appliquez le correctif ou la version corrigée indiqués dans les références de l'éditeur.
- À défaut de correctif, limitez l'exposition (filtrage réseau, désactivation du composant).
- Automatisez la détection : les agents CVE Heimdall (gratuits, open source) corrèlent l'inventaire de vos serveurs avec la base CVE.
Références
- https://www.wordfence.com/threat-intel/vulnerabilities/id/3dee7f76-bd66-4e54-8ef6-bbf581ebcc11?source=cve
- https://plugins.trac.wordpress.org/browser/wpcom-member/tags/1.7.27/includes/social-login.php#L1235
- https://plugins.trac.wordpress.org/browser/wpcom-member/tags/1.7.27/includes/social-login.php#L91
- https://plugins.trac.wordpress.org/browser/wpcom-member/tags/1.7.27/includes/social-login.php#L674
- https://plugins.trac.wordpress.org/browser/wpcom-member/tags/1.7.27/includes/class-sesstion.php#L13
- https://plugins.trac.wordpress.org/browser/wpcom-member/trunk/includes/social-login.php