s2Member – Excellent for All Kinds of Memberships, Content Restriction Paywalls & Member Access Subscriptions — CVE-2026-86596

どんな問題か

The s2Member plugin for WordPress is vulnerable to Remote Code Execution in all versions up to, and including, <= 260927 via the 'item_name' parameter parameter. This is due to insufficient sanitization in strip_php_tags_deep(), which only strips literal '<?' sequences, combined with a post-interpolation placeholder cleanup that reassembles a valid '<?php' opener after the attacker-controlled value has already been embedded in the email template. This makes it possible for authenticated attackers, with custom-level access and above, to execute code on the server.

自分のサイトが該当するかの確認手順

1. WordPressの管理画面にログインし、左メニュー「プラグイン」（またはテーマ）に s2Member – Excellent for All Kinds of Memberships, Content Restriction Paywalls & Member Access Subscriptions があるか確認します。
2. あれば、バージョン番号を見て「対象バージョン」に当てはまるか確認します。
3. 当てはまる場合は「更新」ボタンで修正版へ。使っていないプラグインなら削除します。更新ボタンが出ない・怖くて押せない場合は、保守会社か当社へご相談ください。