CVE-2026-49952 Discuz! X5.0 Authentication Bypass via dbbak.php Encryption Oracle
Unauthenticated attackers can bypass authentication to access database backup and restore functions, potentially modifying data or impersonating users.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- None listed
What is CVE-2026-49952?
CVE-2026-49952 is a critical authentication bypass vulnerability in Discuz! X5.0, published on 15 Jun 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.
Official 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.
Weakness: CWE-323
Which versions are affected by CVE-2026-49952?
How do I fix CVE-2026-49952?
No fix has been published for CVE-2026-49952 yet. Limit exposure of the affected software until one is available.
Upgrade, and rotate credentials and sessions that may have been exposed. More about Authentication bypass.
Is CVE-2026-49952 being exploited?
It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-49952 exists.
Public exploit code: 1 Exploit-DB entry, 1 Nuclei template and 2 proofs of concept on GitHub.
Sources
Also known as GHSA-mx47-h32c-x878.