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VulnerabilityPublished

CVE-2026-29204: WebPros WHMCS · Insecure Direct Object Reference (IDOR)

Affects WebPros WHMCSSource CVE Database V5

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Not known to be exploited · CVSS 9.1 Critical : upgrade to 18.13.3 or 9.0.4 as a priority.

Data as of 30 Oct 2026, 11:52 UTC

CVSS 3.1 base score
9.1Critical
How severe the flaw is on the 0–10 CVSS scale.
EPSS
0.3% chance of exploitation in 30 days – higher than 24% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.
Patch
Available – fixed in 18.13.3, 9.0.4
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N

Exploitation evidence

  1. Disclosed: evidence found.

    CVE published 12 May 2026

  2. Detectable: no evidence on record.

    No public nuclei template indexed

  3. Weaponized: evidence found.

    Public exploit code: GitHub proofs of concept

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

    Not in CISA KEV and no source reports exploitation

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

    No attack traffic recorded by OffSeq Mirage sensors

A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), GitHub proofs of concept, the Metasploit, Exploit-DB and nuclei-templates index as of 30 Oct 2026.

What to do

Upgrade WebPros WHMCS to 18.13.3 or 9.0.4.

Affected software

ProductAffectedFixed in
WebProsWHMCSAffected
  • >=7.4.0 <=18.12.2
  • >=18.13.0 <18.13.3
  • >=9.0.0 <9.0.4
Fixed in
  • 18.13.3
  • 9.0.4
Packagistwhmcs/whmcspkg:composer/whmcs/whmcsOther threatsAffected
  • 7.4.0 – 18.13.0
6 affected builds
Fixed in–

Check your own hosts for these packages with threat-finder (opens in a new tab), our free open-source scanner.

AI-suggested

If you cannot patch yet, restrict access to the client area to trusted users only and monitor for suspicious activity related to addonId parameter usage. Avoid sharing authentication credentials and consider additional application-layer access controls if possible.

Description

CVE-2026-29204 is a critical vulnerability in WebPros WHMCS affecting versions 7.4.0, 18.13.0, and 9.0.0. It involves an insecure direct object reference (IDOR) due to insufficient ownership checks in the clientarea.php component. An authenticated user can submit requests using another user's addonId without proper validation, potentially gaining unauthorized access to the victim's account.

References

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