CVE-2026-49952

CRITICAL EPSS 36.5%
Published Jun 15, 20262w ago · Modified Jun 17, 20261w ago
9.3 CVSS 4.0
Critical
Find Similar
Published Jun 15, 2026 2w ago
Last Modified Jun 17, 2026 1w ago

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.

CVSS Details

Base Score
9.3
Exploitability
—
Impact
—
Vector string
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/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X
Attack Vector Network
Attack Complexity Low
Privileges Required None
User Interaction None
Scope X

Threat Intelligence

EPSS Exploit Probability
36.5% percentile
Exploit & Patch Status
No Known Exploit
No Patch Available

Weaknesses 1

CWE-323

References 5

  • seclists.org http://seclists.org/fulldisclosure/2026/Jun/3
  • gitee.com https://gitee.com/Discuz/DiscuzX/commit/9962dad52c4c6999dabaf91ecd70377c680ff3c6
  • karmainsecurity.com https://karmainsecurity.com/KIS-2026-09
  • karmainsecurity.com https://karmainsecurity.com/chaining-bugs-in-discuz-from-race-condition-to-rce
  • vulncheck.com https://www.vulncheck.com/advisories/discuz-x5-0-authentication-bypass-via-dbbak-php-encryption-oracle

Remediation

No remediation data recorded yet

Check vendor advisories and the NVD entry for patch availability.