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VulnerabilityPublished Updated

CVE-2026-49952: Discuz! X5.0 · Reusing a Nonce, Key Pair in Encryption

Affects Discuz! X5.0Source CVE Database V5

0
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Public exploit available (Exploit-DB) · CVSS 9.3 Critical.

Data as of 30 Oct 2026, 11:52 UTC

CVSS 4.0 base score
9.3Critical
How severe the flaw is on the 0–10 CVSS scale.
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:N

Exploitation evidence

t = 0 is the CVE’s publication on cve.org

  1. Disclosed: evidence found.

    CVE published 15 Jun 2026

  2. Exploited in the wild: no evidence on record.

    Not in CISA KEV and no source reports exploitation

  3. Observed by OffSeq Mirage: no evidence on record.

    No attack traffic recorded by OffSeq Mirage sensors

Timeline

  1. CVE ID reserved

    by VulnCheck

    , 13 days before disclosure

  2. CVE published

    on cve.org

    , t = 0

  3. In Threat Radar

    record ingested

    , 47 minutes after disclosure

  4. 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

ProductAffectedFixed in
Discuz!Discuz! X5.0Affected
  • ≥ 20260320, ≤ 20260501
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

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