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MIME::Field::ParamVal versions before 5.521 for Perl allow one invalid Content-Type parameter to hide the parameters after it, including the multipart boundary

Type: advisorySources: Official CVE List

MIME::Field::ParamVal versions before 5.521 for Perl allow one invalid Content-Type parameter to hide the parameters after it, including the multipart boundary. Parameter parsing stops at the first parameter whose name it cannot read, such as x:y=1 or a name containing an 8-bit byte, and drops every parameter after it. When the boundary is among them, MIME::Parser keeps the multipart body as a single undecoded part without marking the parse as ambiguous. Mail readers that skip the invalid parameter still find the boundary. A remote sender can hide an attachment from a filter that relies on ambiguous_content() while the recipient's mail client shows it.

Products
Not specified
Affected versions
Not specified
Fixed versions
Not specified
CVEs
CVE-2026-116264
Confirmed fixed CVEs
Not specified
Updated in this feed
1 Nov 2026, 20:24 UTC · Revision 1

Source evidence

MIME::Field::ParamVal versions before 5.521 for Perl allow one invalid Content-Type parameter to hide the parameters after it, including the multipart boundary

core-cve · Original source

Published 28 Oct 2026, 17:31 UTC

MIME::Field::ParamVal versions before 5.521 for Perl allow one invalid Content-Type parameter to hide the parameters after it, including the multipart boundary. Parameter parsing stops at the first parameter whose name it cannot read, such as x:y=1 or a name containing an 8-bit byte, and drops every parameter after it. When the boundary is among them, MIME::Parser keeps the multipart body as a single undecoded part without marking the parse as ambiguous. Mail readers that skip the invalid parameter still find the boundary. A remote sender can hide an attachment from a filter that relies on ambiguous_content() while the recipient's mail client shows it.

cve:CVE-2026-116264
Complete source record
{
  "id": "72d3f9b76348890adbe9575a9b72e6f0ecdca294c24ff7bedf1cfacf628ad260",
  "url": "https://www.cve.org/CVERecord?id=CVE-2026-116264",
  "method": "structured",
  "payload": {
    "kind": "advisory",
    "title": "MIME::Field::ParamVal versions before 5.521 for Perl allow one invalid Content-Type parameter to hide the parameters after it, including the multipart boundary",
    "summary": "MIME::Field::ParamVal versions before 5.521 for Perl allow one invalid Content-Type parameter to hide the parameters after it, including the multipart boundary. Parameter parsing stops at the first parameter whose name it cannot read, such as x:y=1 or a name containing an 8-bit byte, and drops every parameter after it. When the boundary is among them, MIME::Parser keeps the multipart body as a single undecoded part without marking the parse as ambiguous. Mail readers that skip the invalid parameter still find the boundary. A remote sender can hide an attachment from a filter that relies on ambiguous_content() while the recipient's mail client shows it.",
    "evidence": "cve:CVE-2026-116264",
    "products": [],
    "severity": "unknown",
    "structured": {
      "id": "CVE-2026-116264",
      "aliases": [
        "CVE-2026-116264"
      ],
      "metrics": [],
      "affected": [
        {
          "repo": "https://salsa.debian.org/dskoll/mime-tools",
          "modules": [
            "MIME::Field::ParamVal"
          ],
          "versions": [
            {
              "status": "affected",
              "version": "0",
              "lessThan": "5.521",
              "versionType": "custom"
            }
          ],
          "packageURL": "pkg:cpan/MIME-tools",
          "packageName": "MIME-tools",
          "programFiles": [
            "lib/MIME/Field/ParamVal.pm"
          ],
          "collectionURL": "https://cpan.org/modules",
          "defaultStatus": "unaffected",
          "programRoutines": [
            {
              "name": "MIME::Field::ParamVal::parse_params"
            }
          ]
        }
      ],
      "modified": "2026-10-28T17:31:52.187Z",
      "provider": "cve",
      "references": [
        "https://metacpan.org/release/DSKOLL/MIME-tools-5.521/changes"
      ],
      "provider_metadata": {
        "cna": {
          "orgId": "9b29abf9-4ab0-4765-b253-1875cd9b441e",
          "shortName": "CPANSec",
          "dateUpdated": "2026-10-28T17:31:52.187Z"
        }
      }
    },
    "related_cves": [
      {
        "value": "CVE-2026-116264",
        "evidence": "/cveMetadata/cveId"
      }
    ],
    "security_relevant": true,
    "severity_evidence": null
  },
  "source_id": "core-cve",
  "document_id": 466439,
  "published_at": "2026-10-28T17:31:52.187+00:00"
}