Discuz! X5.0 releases 20260320 through 20260501 contains an authentication bypass vulnerability that allows unauthenticated remote attackers to gain unauthorized access to database backup and restore functionality by exploiting a shared cryptographic key between UCenter integration and the database backup API exposed by dbbak.php. Attackers can inject a crafted payload through the username parameter during login to abuse the encryption oracle in logging_ctl::logging_more(), obtain a legitimately signed token, and use it to bypass authorization for database export and import operations, with the additional ability to trigger a race condition to impersonate arbitrary users.
PoC: Discuz-X5.0-Authentication-Bypass-Exploit-Framework
Discuz! X5.0 Authentication Bypass Exploit Framework (CVE-2026-49952) - Critical vulnerability allowing unauthenticated database backup access via UC_KEY encryption oracle token reuse. CVSS 9.1. Full-featured tool with version detection, multi-payload attacks, interactive shell, and automated exploitation. Authorized testing only.
PoC: CVE-2026-49952
Chaining Security Bugs in Discuz! X5.0: from Race Condition to Pre-Auth RCE
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N
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