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TI-2026-54274 Aliases CVE-2026-77999GHSA-ffqf-m6vh-866w

Joomla Extension - j2commerce.com - Unauthenticated PayPal callback forgery leading to…

Priority MEDIUM 44CWE-472Published · Updated

Key facts

Attack vector
Network
Privileges required
None
User interaction
None
Attack complexity
Low
Attack requirements
None
Impact type
—
Confidentiality · integrity · availability
None · High · None
Fix status
No fix listed

Attack profile from CVSS 4.0 · CNA. Fix status from CNA.

Summary

Joomla Extension - j2commerce.com - Unauthenticated PayPal callback forgery leading to order confirmation fraud in J2Store 1.0.0-3.3.21, 4.0.0-4.0.21, 4.1.0-4.1.6 - The PayPal IPN listener's signature check (`_validateIPN()`) accepted `UNVERIFIED` and any non-`INVALID` response as valid, made its verification request with `CURLOPT_SSL_VERIFYPEER` disabled, and stored its verdict in a field nothing downstream ever checked — so processing continued regardless of the outcome. Separately, the paid-amount comparison only ran when `mc_gross` was a positive number; omitting the field from the POST body (`floatval(null) == 0`) skipped the check entirely. Combined with a merchant-configured `receiver_email` and a sequential, enumerable order id read from the `custom` field, an anonymous POST was enough to move a pending order straight to `CONFIRMED` with no payment, or force another customer's pending order to `FAILED`. `paypalv2.php` performed no amount check under any circumstances.

Why it matters now

Exploitation None reported CISA SSVC · not in CISA KEV
EPSS 0.00428 37th percentileScored 2026-11-07
Fix No fix listed No fixed version in the sources yet

SSVC decision points

CISA ADP · SSVC 2.0.3

Exploitation
None
Automatable
Yes
Technical impact
Partial

The decision (Track, Attend, Act) also depends on your mission and well-being impact; see CISA's SSVC guide.

Affected products

VendorProductAffected versionsFixed inStatusSource
j2commerce.comJ2Store extension for Joomla1.0.0-3.3.21; 4.0.0-4.0.21; 4.1.0-4.1.6—No fix listedCNA
  • J2Store extension for Joomla Vendorj2commerce.com Affected 1.0.0-3.3.21; 4.0.0-4.0.21; 4.1.0-4.1.6 Fixed in — No fix listed CNA

Remediation

No fixed version listed by the sources yet.

Timeline

  1. 2026-10-02 Threatist record created from CVE-2026-77999
  2. 2026-10-03 Alias added: GHSA-ffqf-m6vh-866w

References

Other 1

  • TI-2026-56676 Joomla Extension - j2commerce.com - Any order can be marked Failed by anyone in J2Store… CVSS 4.0HIGH 8.7
  • TI-2026-56276 Path traversal in j2commerce.com J2Store extension for Joomla CVSS 4.0HIGH 8.7
  • TI-2026-56275 SQL injection in j2commerce.com J2Store extension for Joomla CVSS 4.0HIGH 8.7
  • TI-2026-54302 Authorization bypass in j2commerce.com J2Store extension for Joomla CVSS 4.0HIGH 8.8
  • TI-2026-47655 Authorization bypass in j2commerce.com J2Store extension for Joomla CVSS 4.0HIGH 8.7
  • TI-2026-54304 Missing authorization in j2commerce.com J2Store extension for Joomla CVSS 4.0CRITICAL 9.5
See all 16 →

Sources

This product uses the NVD API but is not endorsed or certified by the NVD. Sources and licences