CVE-2026-49952

CVE-2026-49952 is a critical-severity vulnerability with a CVSS 3.x base score of 9.1. It is not currently listed as actively exploited by CISA, and its EPSS exploit-prediction score is low. The underlying weakness is classified as CWE-323.

Key facts

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.

Frequently asked questions

What is CVE-2026-49952?
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.
How severe is CVE-2026-49952?
CVE-2026-49952 has a CVSS 3.x base score of 9.1, rated critical severity. It is exploitable over network with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is high, integrity high, and availability none.
Is CVE-2026-49952 being actively exploited?
It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 0% (37th percentile), an estimate of the probability of exploitation in the next 30 days.
How do I fix CVE-2026-49952?
Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its critical severity, prioritise patching exposed systems.
Does CVE-2026-49952 have an EU (EUVD) identifier?
Yes. CVE-2026-49952 is tracked in the ENISA EU Vulnerability Database (EUVD) as EUVD-2026-36792.
When was CVE-2026-49952 published?
CVE-2026-49952 was published on 2026-06-15 and last updated on 2026-06-17.

References

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