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Vulnerability record · CVE-2026-19887 · published 5 September 2026

CVE-2026-19887: Deserialization of untrusted data vulnerability

The Welcart e-Commerce plugin for WordPress is vulnerable to PHP Object Injection in all versions up to, and including, 2.12.1 via deserialization of untrusted input in the Telecom EDY payment callback (usces_action_acting_transaction). Unauthenticated attackers can store arbitrary 'reserve' key/value pairs as order metadata during a public checkout, then invoke the callback with an attacker-chosen 'option' parameter to select and unserialize that metadata without any provider signature, source-address, transaction-identity or ownership check. A POP chain is present in the TCPDF library bundled with the plugin itself, so no additional plugin or theme is required. This makes it possible for unauthenticated attackers to delete arbitrary files on the server, including wp-config.php, which can lead to remote code execution when an attacker re-runs the WordPress installer against a database they control. Successful exploitation is contingent on an admin printing an invoice to trigger file deletion.

8.8 CVSS 3.1 High EPSS 0.57% · top 54.9% CWE-502 · Deserialization of untrusted data Deferred
8.8CVSS 3.1 base score
0.57%EPSS exploitation probability, 30 days
NoNot in CISA KEV
0Affected product versions listed by NVD
10References
8 Sep 2026Last modified by NVD

Description

The Welcart e-Commerce plugin for WordPress is vulnerable to PHP Object Injection in all versions up to, and including, 2.12.1 via deserialization of untrusted input in the Telecom EDY payment callback (usces_action_acting_transaction). Unauthenticated attackers can store arbitrary 'reserve' key/value pairs as order metadata during a public checkout, then invoke the callback with an attacker-chosen 'option' parameter to select and unserialize that metadata without any provider signature, source-address, transaction-identity or ownership check. A POP chain is present in the TCPDF library bundled with the plugin itself, so no additional plugin or theme is required. This makes it possible for unauthenticated attackers to delete arbitrary files on the server, including wp-config.php, which can lead to remote code execution when an attacker re-runs the WordPress installer against a database they control. Successful exploitation is contingent on an admin printing an invoice to trigger file deletion.

CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H

References

LinkTags
https://plugins.trac.wordpress.org/browser/usc-e-shop/trunk/classes/cart.class.php#L546
https://plugins.trac.wordpress.org/browser/usc-e-shop/trunk/classes/orderData.class.php#L41
https://plugins.trac.wordpress.org/browser/usc-e-shop/trunk/functions/function.php#L218
https://plugins.trac.wordpress.org/browser/usc-e-shop/trunk/functions/hoock_func.php#L517
https://plugins.trac.wordpress.org/browser/usc-e-shop/trunk/includes/order_print.php#L16
https://plugins.trac.wordpress.org/browser/usc-e-shop/trunk/pdf/tcpdf/tcpdf.php#L7794
https://plugins.trac.wordpress.org/changeset/3673344/usc-e-shop/trunk/classes/orderData.class.php
https://plugins.trac.wordpress.org/changeset?old_path=%2Fusc-e-shop/tags/2.12.1&new_path=%2Fusc-e-shop/tags/2.12.2
https://plugins.trac.wordpress.org/changeset?reponame=&new=3673346%40usc-e-shop%2Ftags%2F2.12.2&old=3651925%40usc-e-shop
https://www.wordfence.com/threat-intel/vulnerabilities/id/716a7c3c-2e26-4da9-a299-7dcbaa7e4895?source=cve

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Source: NIST National Vulnerability Database (record CVE-2026-19887), CISA KEV, FIRST EPSS (scores of 2026-09-26). This page is refreshed as NVD updates the record.