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

{
  "id": "41a75fa87deaec907727f68244ecd0c01759e5e9656da219b7069cee37d072b5",
  "url": "https://osv.dev/vulnerability/CVE-2026-19872",
  "method": "structured",
  "payload": {
    "kind": "advisory",
    "title": "HTML::FormHandler versions before 0.410000 for Perl allow cross-site scripting via a submitted value rendered unescaped in an error message",
    "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:CVE-2026-19872",
    "products": [],
    "severity": "medium",
    "structured": {
      "id": "CVE-2026-19872",
      "aliases": [
        "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"
        }
      ],
      "affected": [
        {
          "ranges": [
            {
              "repo": "https://github.com/gshank/html-formhandler",
              "type": "GIT",
              "events": [
                {
                  "introduced": "0"
                },
                {
                  "fixed": "4aa24166e3a5cdbc3b64aa8a63c9d4ca8c529f34"
                },
                {
                  "fixed": "2574fdb4561f5c32d44cfbfbb3188345d49eb5a2"
                }
              ],
              "database_specific": {
                "extracted_events": [
                  {
                    "range": [
                      {
                        "introduced": "0"
                      },
                      {
                        "fixed": "0.410000"
                      }
                    ],
                    "source": "AFFECTED_FIELD",
                    "strategy": "StandardRange"
                  },
                  {
                    "range": [
                      {
                        "fixed": "2574fdb4561f5c32d44cfbfbb3188345d49eb5a2"
                      }
                    ],
                    "source": "REFERENCES_COMMIT"
                  }
                ]
              }
            }
          ],
          "versions": [
            "0.40068",
            "0.40067",
            "0.40066",
            "0.40065",
            "0.40064",
            "0.40063",
            "0.40062",
            "0.40061",
            "0.40060",
            "0.40059",
            "0.40058",
            "0.40057",
            "0.40056",
            "0.40055",
            "0.40054",
            "0.40053",
            "0.40052",
            "0.40051",
            "0.40050",
            "0.40028",
            "0.40027",
            "0.40026",
            "0.40025",
            "0.40024",
            "0.40023",
            "0.40022",
            "0.40021",
            "0.40020",
            "0.40019",
            "0.40018",
            "0.40017",
            "0.40016",
            "0.40015",
            "0.40014",
            "0.40013",
            "0.40012",
            "0.40011",
            "0.40010",
            "0.40009",
            "0.40008",
            "0.40007",
            "0.40006",
            "0.40005",
            "0.40004",
            "0.40003",
            "0.40002",
            "0.40001",
            "0.40000",
            "0.36001",
            "0.36000",
            "0.35005",
            "0.35003",
            "0.35002",
            "0.35001",
            "0.35000",
            "0.34001",
            "0.34000",
            "0.33002",
            "0.33001",
            "0.31003",
            "0.27003",
            "0.27002",
            "0.27",
            "0.23",
            "0.22",
            "ver-0.20",
            "ver17+",
            "ver15",
            "roles",
            "ver13",
            "ver12",
            "ver10",
            "inherit_has_fields",
            "dup_fields_order",
            "ver09",
            "has_field",
            "ver08",
            "after-persist",
            "empty-row"
          ],
          "database_specific": {
            "source": "https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-19872.json"
          }
        }
      ],
      "modified": "2026-10-28T02:30:23.378581842Z",
      "provider": "osv",
      "references": [
        "https://cpan.org/modules",
        "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/19xxx/CVE-2026-19872.json",
        "https://metacpan.org/release/ABRAXXA/HTML-FormHandler-0.410000/changes",
        "https://nvd.nist.gov/vuln/detail/CVE-2026-19872",
        "https://github.com/gshank/html-formhandler/commit/2574fdb4561f5c32d44cfbfbb3188345d49eb5a2.patch",
        "https://github.com/gshank/html-formhandler"
      ],
      "provider_metadata": {
        "cwe_ids": [
          "CWE-79"
        ],
        "cna_assigner": "CPANSec",
        "osv_generated_from": "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/19xxx/CVE-2026-19872.json"
      }
    },
    "related_cves": [
      {
        "value": "CVE-2026-19872",
        "evidence": "/id"
      }
    ],
    "security_relevant": true,
    "severity_evidence": "/severity/0/score"
  },
  "source_id": "core-osv",
  "document_id": 489585,
  "published_at": "2026-09-08T20:08:21.896+00:00"
}