CVE-2026-49952

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.

Affected products

Discuzx

Fix

Available

CVSS 4.0

9.3 CRITICAL

CVSS 3.1

9.1 CRITICAL

EPSS

4.7% (91th percentile)

Weakness

CWE-323

NVD status

Deferred

Published

2026-06-15