Microsoft Security Response Center guidance
Vendor revision: Nov 7, 2026Release Notes
Vulnerability intelligence
CVE-2026-120640. It is not in the current CISA KEV record we collected. That does not prove exploitation has not occurred.
Release Notes
CGI versions before 5.00 for Perl allow the POSTDATA, PUTDATA, PATCHDATA and XForms:Model parameters to be set from the query string or form fields.
CGI stores a non-form request body under POSTDATA, PUTDATA or PATCHDATA, and an XForms body under XForms:Model, but also accepts these names from the query string, a form field or a multipart part, so an application cannot tell a client-sent value from the real body.
A cross-site HTML form can post POSTDATA={"admin":true} to an endpoint that reads JSON from param('POSTDATA'), a request forgery that needs no CORS preflight.
Source: NVD