---
id: CVE-2026-120635
title: >-
  CGI versions before 5.00 for Perl allow form fields to be smuggled past
  proxies and WAFs via multipart parsing that differs from the RFCs
summary: >-
  CGI versions before 5.00 for Perl allow form fields to be smuggled past
  proxies and WAFs via multipart parsing that differs from the RFCs.


  The multipart/form-data parser matches the boundary anywhere rather than at
  the start of a line, …
severity: none
cwe:
  - CWE-436
product: CGI
affected:
  - CGI < 5.00
published: '2026-11-03'
updated: '2026-11-03'
sourceUpdated: '2026-11-03T23:40:15.070Z'
source: CVEORG
sourceUrl: 'https://www.cve.org/CVERecord?id=CVE-2026-120635'
references:
  - url: 'https://www.rfc-editor.org/rfc/rfc2046#section-5.1.1'
  - url: 'https://metacpan.org/release/LEEJO/CGI-4.72/source/lib/CGI.pm'
  - url: 'https://metacpan.org/release/LEEJO/CGI-5.00/changes'
  - url: >-
      https://github.com/leejo/CGI.pm/commit/f719fc08e8756708bcd4f1e357d5c0f8702f85dd.patch
  - url: >-
      https://github.com/leejo/CGI.pm/commit/cbf04979f9974458ac223793bbd9d0b6a772aa66.patch
  - url: >-
      https://github.com/leejo/CGI.pm/commit/fe9516804d59a3774e280c15dbb7072fbd0ba5f1.patch
  - url: >-
      https://github.com/leejo/CGI.pm/commit/e0ef8f4248c6ae3025749040d8595d206b6a1b49.patch
tags:
  - cve.org
epss: 0.00198
epssPercentile: 0.09753
ingestedAt: '2026-11-05T20:33:06.614Z'
---

## Overview

CGI versions before 5.00 for Perl allow form fields to be smuggled past proxies and WAFs via multipart parsing that differs from the RFCs.

The multipart/form-data parser matches the boundary anywhere rather than at the start of a line, uses the boundary without its leading -- for some client-supplied User-Agent values, finds the Content-Disposition name and filename inside the quoted values of other parameters, and corrupts parts when the boundary nears the 4096-byte read size.

## Affected

- `CGI < 5.00`

## Remediation

Upgrade to CGI 5.00 or later.