CVE-2026-49952: Discuz! X5.0 · Reusing a Nonce, Key Pair in Encryption
Affects Discuz! X5.0Source CVE Database V5
Public exploit available (Exploit-DB) · CVSS 9.3 Critical.
Data as of 30 Oct 2026, 11:52 UTC
- EPSS
- 4.7% chance of exploitation in 30 days – higher than 91% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.
CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:H/VA:N/SC:N/SI:N/SA:NExploitation evidence
t = 0 is the CVE’s publication on cve.org
Disclosed: evidence found.
CVE published 15 Jun 2026
Detectable: evidence found.
Weaponized: evidence found.
Exploited in the wildExploited: no evidence on record.
Not in CISA KEV and no source reports exploitation
Observed by OffSeq MirageSeen by Mirage: no evidence on record.
No attack traffic recorded by OffSeq Mirage sensors
Timeline
CVE ID reserved
by VulnCheck
, 13 days before disclosure
CVE published
on cve.org
, t = 0
In Threat Radar
record ingested
, 47 minutes after disclosure
First Exploit-DB entry (opens in a new tab)
Discuz! X5.0 - Authentication Bypass
, 22 days after disclosure
A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), the Metasploit, Exploit-DB and nuclei-templates index as of 30 Oct 2026.
What to do
Affected software
| Product | Affected | Fixed in |
|---|---|---|
| Discuz!Discuz! X5.0 | Affected
| Fixed in– |
AI-suggested
Until a patch is available, restrict access to the vulnerable API endpoints and monitor for suspicious activity related to database backup and restore operations. Avoid exposing the dbbak.php interface publicly.
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.
References
- karmainsecurity.com/KIS-2026-09 (opens in a new tab)
- karmainsecurity.com/chaining-bugs-in-discuz-from-race-condition-to-rce (opens in a new tab)
- gitee.com/Discuz/DiscuzX/commit/9962dad52c4c6999dabaf91ecd70377c680ff3c6 (opens in a new tab)
- vulncheck.com/advisories/discuz-x5-0-authentication-bypass-via-dbbak-php-encryption-oracle (opens in a new tab)
- seclists.org/fulldisclosure/2026/Jun/3 (opens in a new tab)