CVE-2026-49952 is a critical-severity vulnerability (CVSS 9.1).
Summary
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.
Remediation
Apply the vendor’s update during your next patch window and verify exposure. Patch-management tools that can deploy and verify the fix include Action1, Automox, ManageEngine Patch Manager Plus, ManageEngine Endpoint Central. See our best patch management ranking.
Sources
- https://gitee.com/Discuz/DiscuzX/commit/9962dad52c4c6999dabaf91ecd70377c680ff3c6
- https://karmainsecurity.com/KIS-2026-09
- https://karmainsecurity.com/chaining-bugs-in-discuz-from-race-condition-to-rce
- https://www.vulncheck.com/advisories/discuz-x5-0-authentication-bypass-via-dbbak-php-encryption-oracle