---
id: CVE-2026-19872
title: >-
  HTML::FormHandler versions before 0.410000 for Perl allow cross-site scripting
  via a submitted value rendered unescaped in an error message.


  The wrappers and renderers that emit a form's errors interpolate the error
  string straight into…
summary: >-
  HTML::FormHandler versions before 0.410000 for Perl allow cross-site scripting
  via a submitted value rendered unescaped in an error message.


  The wrappers and renderers that emit a form's errors interpolate the error
  string straight into…
severity: medium
cvss: 6.1
cvssVector: 'CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N'
cwe:
  - CWE-79
product: HTML-FormHandler
affected:
  - HTML-FormHandler < 0.410000
published: '2026-09-08'
updated: '2026-09-10'
sourceUpdated: '2026-09-10T18:17:58.827'
source: NVD
sourceUrl: 'https://nvd.nist.gov/vuln/detail/CVE-2026-19872'
references:
  - url: >-
      https://github.com/gshank/html-formhandler/commit/2574fdb4561f5c32d44cfbfbb3188345d49eb5a2.patch
    label: 9b29abf9-4ab0-4765-b253-1875cd9b441e
  - url: 'https://metacpan.org/release/ABRAXXA/HTML-FormHandler-0.410000/changes'
    label: 9b29abf9-4ab0-4765-b253-1875cd9b441e
  - url: 'http://www.openwall.com/lists/oss-security/2026/09/08/15'
    label: af854a3a-2127-422b-91ae-364da2661108
  - url: >-
      https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-19872.json
  - url: 'https://access.redhat.com/security/cve/CVE-2026-19872'
  - url: 'https://www.cve.org/CVERecord?id=CVE-2026-19872'
tags:
  - nvd
  - cve.org
  - csaf
  - vex
  - red-hat
ssvc:
  exploitation: none
  automatable: 'no'
  technicalImpact: partial
  timestamp: '2026-09-10T17:51:07.811981Z'
epss: 0.00255
epssPercentile: 0.15183
ingestedAt: '2026-09-08T21:11:12.314Z'
vendor: Red Hat
scores:
  nvd: 6.1
  vendor: 5.4
---

## Overview

HTML::FormHandler versions before 0.410000 for Perl allow cross-site scripting via a submitted value rendered unescaped in an error message.

The wrappers and renderers that emit a form's errors interpolate the error string straight into HTML with no escaping. Two of the library's own messages, no_match and not_allowed, splice the submitted value into that string, and a failing type constraint puts the rejected value into the message it builds, which _apply_actions hands to add_error.

A field declared with a check regexp, a check list or a type constraint reaches those messages, with no custom validator and no non-default configuration. Errors rendered through an application's own escaping template layer rather than the library's rendering roles are not affected.

A request over the network that submits markup to such a field gets it back live inside the error span, running script in the victim's origin. Re-rendering a rejected value later gives the stored variant.

## Remediation

Refer to the linked advisories for vendor-supplied fixes and affected version ranges.

## Vendor advisories

- **Red Hat VEX** · updated 2026-09-14 · [vex](https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-19872.json)