Critical

CVE-2026-49952: Security Advisory

CVE-2026-49952 CVSS 9.1
Who it affects
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.
What to do
Apply the vendor's update in your next patch window.
Deploy the fix with Action1AutomoxManageEngine Patch Manager PlusManageEngine Endpoint Central Are you exposed? Compare patch tools →

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

Data as of June 16, 2026. Sources: nvd.nist.gov, gitee.com, karmainsecurity.com, karmainsecurity.com, vulncheck.com. Figures are pulled from public vendor and security data and refreshed automatically.