---
id: "CVE-2026-120646"
kind: "vulnerability"
aliases: ["CVE-2026-120646"]
title: "Perl CGI: plain string input crashes uploadInfo, denying service"
severity: "low"
cvss: null
epss: null
exploited: false
status: "open"
category: "package"
products: []
ecosystems: []
tags: ["cgi", "package", "perl", "self-hosted"]
not_affected_if: ["cgi-5.00-or-later", "no-upload-handling"]
published_at: "2026-11-04T00:17:26+00:00"
first_seen_at: "2026-11-04T00:46:17+00:00"
updated_at: "2026-11-04T00:48:09+00:00"
sources: [{"source": "nvd", "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-120646", "first_seen_at": "2026-11-04T00:46:17+00:00"}]
---

# Perl CGI: plain string input crashes uploadInfo, denying service

The Perl CGI module from 4.71 before 5.00 calls a method on a string the caller controls when it should check for an upload filehandle. A crafted request parameter makes the call die, which stops the script handling that request.

_Summary, check and fix written by a model from the sources; labelled as such._

## How to check

- `perl -MCGI -e 'print $CGI::VERSION'` to read the installed CGI module version
- Search application code and dependency lockfiles for `CGI` and call sites of `uploadInfo`

## Fix

- Move to CGI `5.00` or later (per the sources; the fixed version is stated in the patch linked from the NVD entry)

## Timeline

- 2026-11-04T00:46:17+00:00 nvd https://nvd.nist.gov/vuln/detail/CVE-2026-120646

## Documents

- [fix] Patch: github.com https://github.com/leejo/CGI.pm/commit/a14a7decfdc18f2daf436d30df9b543e3f0f8da3.patch

## From the sources

CGI versions from 4.71 before 5.00 for Perl allow denial of service via a plain string dereferenced as a symbolic reference in uploadInfo.

uploadInfo dereferences its argument and calls its filename method without checking that it is an upload filehandle. A plain string naming a defined global variable, such as the parameter value from ?upload=0, is treated as a symbolic reference, and the method call on it dies.

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