libhtml-formhandler-perl — security advisory
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.
- Products
- libhtml-formhandler-perl
- Affected versions
- 0.40057-1, 0.40064-1, 0.40067-1, 0.40068-1, 0.40068-2, 0.40068-3
- Fixed versions
- Not specified
- CVEs
- CVE-2026-19872
- Confirmed fixed CVEs
- Not specified
- Updated in this feed
- 31 Oct 2026, 02:42 UTC · Revision 1
Source evidence
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.
osv:UBUNTU-CVE-2026-19872
libhtml-formhandler-perl
Fixed versions: Not specified
libhtml-formhandler-perl
Fixed versions: Not specified
libhtml-formhandler-perl
Fixed versions: Not specified
libhtml-formhandler-perl
Fixed versions: Not specified
libhtml-formhandler-perl
Fixed versions: Not specified
libhtml-formhandler-perl
Fixed versions: Not specified
libhtml-formhandler-perl
Fixed versions: Not specified
Complete source record
{
"id": "b0dc8d2ca8060ea0b4efc85f7dc37db1cf28d1af88a6f4adb7bb7978f532da06",
"url": "https://osv.dev/vulnerability/UBUNTU-CVE-2026-19872",
"method": "structured",
"payload": {
"kind": "advisory",
"title": "UBUNTU-CVE-2026-19872",
"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 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.",
"evidence": "osv:UBUNTU-CVE-2026-19872",
"products": [
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{
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{
"name": {
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"affected_versions": [
{
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"evidence": "/affected/6/versions"
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],
"severity": "medium",
"structured": {
"id": "UBUNTU-CVE-2026-19872",
"aliases": [
"UBUNTU-CVE-2026-19872"
],
"metrics": [
{
"type": "CVSS_V3",
"score": "CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N"
},
{
"type": "Ubuntu",
"score": "medium"
}
],
"affected": [
{
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"ecosystem": "Ubuntu:16.04:LTS"
},
"versions": [
"0.40057-1",
"0.40064-1"
],
"database_specific": {
"source": "https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-19872.json"
},
"ecosystem_specific": {
"binaries": [
{
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"package": {
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"versions": [
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"database_specific": {
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],
"modified": "2026-10-17T12:58:47.109600736Z",
"provider": "osv",
"upstream": [
"CVE-2026-19872"
],
"references": [
"https://ubuntu.com/security/CVE-2026-19872",
"https://www.cve.org/CVERecord?id=CVE-2026-19872",
"https://lists.security.metacpan.org/cve-announce/msg/43387502/"
]
},
"related_cves": [
{
"value": "CVE-2026-19872",
"evidence": "/upstream"
}
],
"security_relevant": true,
"severity_evidence": "/severity/0/score"
},
"source_id": "core-osv",
"document_id": 359048,
"published_at": "2026-09-08T20:17:00+00:00"
}