# CVE-2026-49952

## Summary

- **CVE ID:** CVE-2026-49952
- **Severity:** CRITICAL
- **CVSS Score:** 9.3 (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)
- **CWE:** CWE-323
- **Published:** Jun 15, 2026
- **Last Modified:** Jul 28, 2026

## 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! — Discuz! X5.0 (20260320)

## References

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

## Exploitation Prediction (EPSS)

- **EPSS Score:** 4.72%
- **EPSS Percentile:** 91.3

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_Exported from OnDuty AI Vulnerability Intelligence on 2026-09-10._