# CVE-2026-120636: CGI versions before 5.00 for Perl allow open redirects and script injection via URLs built from REQUEST_URI in url and start_form

Status: published. Published: 2026-11-03. Updated: 2026-11-03.

CGI versions before 5.00 for Perl allow open redirects and script injection via URLs built from REQUEST_URI in url and start_form.

url(-absolute=>1), url(-relative=>1) and the default start_form action are built from the client-supplied REQUEST_URI without validation. The result can be protocol-relative (//evil.example), absolute-form (http://evil.example/) or contain backslashes, and url(-relative=>1) can return a javascript: URL. Links and form posts built from these URLs can go to another host.

## Remediation

- fix: Upgrade to CGI 5.00 or later. (source: CNA: CPANSec)
- fix: The reporting source identifies this reference as a patch. Check the advisory for affected versions and supported release branches. (source: CNA: CPANSec) — https://github.com/leejo/CGI.pm/commit/9405ef3909ee94991a3474167aa53b9051bd8765.patch

## Affected products and versions

-  /  (CGI): ≥ 0; < 5.00 (affected, custom). Source: CNA: CPANSec

## Severity and prioritization

- CISA KEV: No listing in collected sources

- EPSS: Not available

- SSVC: Not available

- Weaknesses: CWE-601, CWE-79

## Exploit evidence

No exploit evidence in collected sources. This is not proof of no exploitation.

## References

- https://metacpan.org/release/LEEJO/CGI-4.72/source/lib/CGI.pm (CNA: CPANSec; technical-description)

- https://metacpan.org/release/LEEJO/CGI-5.00/changes (CNA: CPANSec; release-notes)

- https://github.com/leejo/CGI.pm/commit/9405ef3909ee94991a3474167aa53b9051bd8765.patch (CNA: CPANSec; patch)

## Provenance

- CNA: CPANSec: https://www.cve.org/CVERecord?id=CVE-2026-120636; retrieved 2026-11-04; source updated 2026-11-03

Revision: 891866c3e91e3b53ee59f54807de513b8c9aa650227c6b80b0e0be3d0880278e

Canonical: https://y2.dev/cve/CVE-2026-120636

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