Description
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.
Published: 2026-11-03
Score: 6.5 Medium
EPSS: < 1% Very Low
KEV: No
Impact: n/a
Action: n/a
AI Analysis

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Remediation

Vendor Solution

Upgrade to CGI 5.00 or later.


Vendor Workaround

For deployments that cannot upgrade, check the request Content-Type before trusting param('POSTDATA').

Tracking

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Advisories

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History

Wed, 04 Nov 2026 12:15:00 +0000

Type Values Removed Values Added
Weaknesses CWE-454
References
Metrics threat_severity

None

cvssV3_1

{'score': 6.5, 'vector': 'CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:H/A:N'}

threat_severity

Moderate


Wed, 04 Nov 2026 00:00:00 +0000

Type Values Removed Values Added
Description 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.
Title 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
Weaknesses CWE-352
References

Subscriptions

No data.

cve-icon MITRE

Status: PUBLISHED

Assigner: CPANSec

Published:

Updated: 2026-11-03T23:40:33.770Z

Reserved: 2026-11-02T17:41:07.710Z

Link: CVE-2026-120640

cve-icon Vulnrichment

No data.

cve-icon NVD

Status : Deferred

Published: 2026-11-04T00:17:25.390

Modified: 2026-11-04T18:42:35.810

Link: CVE-2026-120640

cve-icon Redhat

Severity : Moderate

Publid Date: 2026-11-03T23:40:33Z

Links: CVE-2026-120640 - Bugzilla

cve-icon OpenCVE Enrichment

Updated: 2026-11-04T13:45:14Z

Weaknesses
  • CWE-352

    Cross-Site Request Forgery (CSRF)

  • CWE-454

    External Initialization of Trusted Variables or Data Stores