What’s Vulnerable › Vulnerabilities

CVE-2026-49952: Discuz! X5.0 Authentication Bypass via dbbak.php Encryption Oracle

• Severity: critical (CVSS 9.1 v3.1)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 4.7% probability of exploitation in the next 30 days
• Public exploit or detection template: yes
• Published: 2026-06-15 · updated 2026-10-25
• Weakness: CWE-323

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.

Affected products

• Discuz! X5.0: from 20260320 through 20260501

References

• 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
• http://seclists.org/fulldisclosure/2026/Jun/3

Get alerted when CVE-2026-49952 or the next vulnerability affects your stack