CVE-2026-49952
CriticalPublic exploitDiscuz!
Published Jun 15, 2026 · Updated Jul 28, 2026
Key Facts
Patch immediately- CVE-2026-49952 is a critical-severity vulnerability (CVSS 9.3 v4) affecting Discuz! X5.0.
- It is not listed in any known-exploited vulnerabilities catalog. Public exploit code is available.
- EPSS estimates a 3.7% probability of exploitation in the next 30 days.
- No fixed version is listed yet; check the vendor advisory for mitigations.
- Brandefense priority: patch immediately, because public exploit code exists for a high-severity flaw.
CVSS v4
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
EPSS (30-day exploit likelihood)
3.7%
Higher than 89.4% of all scored CVEs
Exploited in the wild
No known
Not in a known-exploited catalog
Public exploit code
Available
Proof-of-concept or weaponized module
Get the full CVE-2026-49952 brief as a PDF
Every affected product and fixed release, exploitation status and a first 24 hours response checklist, emailed within minutes.
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
1 affected entries in total| Product | Affected versions | Fixed in |
|---|---|---|
| Discuz! X5.0 | >= 20260320 | n/a |
Timeline
Publicly disclosed
Jun 15, 2026
Last updated
Jul 28, 2026
Weakness Type
- CWE-323 Reusing a Nonce, Key Pair in Encryption
References
- exploitExploitDB-52621
- otherhttp://seclists.org/fulldisclosure/2026/Jun/3
- otherhttps://gitee.com/Discuz/DiscuzX/commit/9962dad52c4c6999dabaf91ecd70377c680ff3c6
- otherhttps://karmainsecurity.com/chaining-bugs-in-discuz-from-race-condition-to-rce
- otherhttps://karmainsecurity.com/KIS-2026-09
FAQ
Common Questions.
Discuz!
Affected: Discuz! X5.0 versions >= 20260320. The full list is in the CVE brief.
It is not listed in any known-exploited vulnerabilities catalog.
No, it is not currently listed in the CISA Known Exploited Vulnerabilities catalog.
Public exploit code is available.
No fixed version is listed yet; check the vendor advisory for mitigations.
Brandefense priority: patch immediately, because public exploit code exists for a high-severity flaw.
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