# CVE-2026-19872: libhtml-formhandler-perl: HTML::FormHandler versions before 0.410000 for Perl allow cross-site scripting via a submitted value rendered unescap...

CVE-2026-19872 is fixed in libhtml-formhandler-perl on 1 platform by DEBIAN-CVE-2026-19872 (version 0.410002-1), released September 17, 2026. It is not reported as exploited. Patch Radar priority: Routine.

- Web page: https://patchblox.com/security/cve/CVE-2026-19872
- Priority: Routine
- CVSS: 6.1 (medium)
- EPSS: 0.0033
- CISA KEV: not listed
- Exploited (vendor report): no
- Publicly disclosed: no
- Published: Sep 8, 2026

## Description

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.

## Where it's fixed

| Platform | Product | Fixed in | Fix | Released |
|---|---|---|---|---|
| Linux | libhtml-formhandler-perl Debian 14 | 0.410002-1 | [DEBIAN-CVE-2026-19872](https://patchblox.com/security/data/fix/linux/debian-cve-2026-19872.md) | Sep 17, 2026 |

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Data as of 2026-11-08T19:12:23Z UTC. Source: Patchblox Patch Radar (https://patchblox.com/security/patch-radar). Patchblox finds out-of-date software on Windows, macOS and Linux and updates it through release rings: https://patchblox.com/demo

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