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.

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Advisories

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Fixes

Solution

Upgrade to CGI 5.00 or later.


Workaround

For deployments that cannot upgrade, reject Content-Type request headers longer than 1KB at the web server.

History

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

Type Values Removed Values Added
References
Metrics threat_severity

None

cvssV3_1

{'score': 5.3, 'vector': 'CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L'}

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 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.
Title CGI versions before 5.00 for Perl allow CPU exhaustion via a backtracking regex on the XForms multipart/related Content-Type
Weaknesses CWE-1333
References

Projects

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cve-icon MITRE

Status: PUBLISHED

Assigner: CPANSec

Published:

Updated: 2026-11-03T23:40:01.071Z

Reserved: 2026-11-02T17:39:55.528Z

Link: CVE-2026-120632

cve-icon Vulnrichment

No data.

cve-icon NVD

Status : Deferred

Published: 2026-11-04T00:17:24.320

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

Link: CVE-2026-120632

cve-icon Redhat

Severity : Moderate

Publid Date: 2026-11-03T23:40:01Z

Links: CVE-2026-120632 - Bugzilla

cve-icon OpenCVE Enrichment

Updated: 2026-11-04T14:15:15Z

Weaknesses