Paymenter up to 1.4.x PayPal webhook endpoint file_get_contents PAYPAL-CERT-URL server-side request forgery

Summaryinfo

A vulnerability described as critical has been identified in Paymenter up to 1.4.x. This affects the function file_get_contents of the file /extensions/paypal/webhook of the component PayPal webhook endpoint. Such manipulation of the argument PAYPAL-CERT-URL leads to server-side request forgery. This vulnerability is documented as CVE-2026-44583. The attack can be executed remotely. There is not any exploit available.

Detailsinfo

A vulnerability, which was classified as critical, has been found in Paymenter up to 1.4.x. Affected by this issue is the function file_get_contents of the file /extensions/paypal/webhook of the component PayPal webhook endpoint. The manipulation of the argument PAYPAL-CERT-URL with an unknown input leads to a server-side request forgery vulnerability. Using CWE to declare the problem leads to CWE-918. The web server receives a URL or similar request from an upstream component and retrieves the contents of this URL, but it does not sufficiently ensure that the request is being sent to the expected destination. Impacted is confidentiality, integrity, and availability. CVE summarizes:

Paymenter is a free and open-source webshop solution for management of hosting services. In versions prior to 1.5.0, the PayPal webhook endpoint /extensions/paypal/webhook processes the PAYPAL-CERT-URL HTTP header without validation, allowing attackers to control server-side HTTP request destinations. This value is passed directly into a server-side HTTP request via file_get_contents, allowing attackers to control the destination of the request. No allowlist, validation, or signature verification is applied to the header before usage. As a result, the application can be coerced into performing HTTP requests to attacker-controlled or internal network destinations. This vulnerability allows remote unauthenticated attackers to induce server-side HTTP GET requests to arbitrary external or internal endpoints. Depending on network configuration, this may lead to: blind SSRF to external attacker-controlled systems, and potential access to internal network services No direct response data is returned to the attacker (blind SSRF), but the issue may still enable sensitive network probing or data exfiltration via side channels. This issue has been fixed in version 1.5.0.

The advisory is shared for download at github.com. This vulnerability is handled as CVE-2026-44583 since 05/06/2026. The exploitation is known to be easy. The attack may be launched remotely. No form of authentication is required for exploitation. There are known technical details, but no exploit is available.

Upgrading to version 1.5.0 eliminates this vulnerability.

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Productinfo

Name

• Paymenter

Version

• 1.0
• 1.1
• 1.2
• 1.3
• 1.4

Website

• Product: https://github.com/Paymenter/Paymenter/

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