# CVE-2026-120632: CGI versions before 5.00 for Perl allow CPU exhaustion via a backtracking regex on the XForms multipart/related Content-Type

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

CGI versions before 5.00 for Perl allow CPU exhaustion via a backtracking regex on the XForms multipart/related Content-Type.

When a POST Content-Type contains multipart/related, the boundary and start parameters are extracted with an unanchored pattern that puts .+ on either side of the boundary capture, which backtracks in cubic time on a header that does not match. No request body is needed.

## Remediation

- fix: Upgrade to CGI 5.00 or later. (source: CNA: CPANSec)
- workaround: For deployments that cannot upgrade, reject Content-Type request headers longer than 1KB at the web server. (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/1e529c7ac8d410a51b4b04ab9d6cc00d51ef33c0.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-1333

## 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/1e529c7ac8d410a51b4b04ab9d6cc00d51ef33c0.patch (CNA: CPANSec; patch)

## Provenance

- CNA: CPANSec: https://www.cve.org/CVERecord?id=CVE-2026-120632; retrieved 2026-11-04; source updated 2026-11-03

Revision: 17f46a57aef56e3f963c4afda53231f7ea696ebe90258def0a4978f3cb3a405f

Canonical: https://y2.dev/cve/CVE-2026-120632

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