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.
History

Mon, 15 Jun 2026 20:30:00 +0000

Type Values Removed Values Added
Metrics ssvc

{'options': {'Automatable': 'yes', 'Exploitation': 'poc', 'Technical Impact': 'total'}, 'version': '2.0.3'}


Mon, 15 Jun 2026 19:30:00 +0000

Type Values Removed Values Added
Description 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.
Title Discuz! X5.0 Authentication Bypass via dbbak.php Encryption Oracle
Weaknesses CWE-323
References
Metrics cvssV3_1

{'score': 9.1, 'vector': 'CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N'}

cvssV4_0

{'score': 9.3, 'vector': 'CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:H/VA:N/SC:N/SI:N/SA:N'}


cve-icon MITRE

Status: PUBLISHED

Assigner: VulnCheck

Published:

Updated: 2026-06-15T19:59:18.533Z

Reserved: 2026-06-02T16:30:15.232Z

Link: CVE-2026-49952

cve-icon Vulnrichment

Updated: 2026-06-15T19:59:10.619Z

cve-icon NVD

Status : Received

Published: 2026-06-15T20:16:29.103

Modified: 2026-06-15T20:16:29.103

Link: CVE-2026-49952

cve-icon Redhat

No data.

cve-icon OpenCVE Enrichment

No data.