CVE-2026-116266

Full vulnerability record from the local CVENow database.

Description

MIME::Head versions from 5.518 before 5.521 for Perl decode a partly encoded multipart boundary without flagging the parse as ambiguous. The multipart_boundary() method decodes RFC 2047 encoded words anywhere in the boundary, but the ambiguity check only fires when the whole value is one encoded word. A boundary such as abc=?us-ascii?Q?def?= is used as abcdef, and ambiguous_content() returns false. Encoded words are not allowed in parameters, so other mail readers split the message on the literal value. A remote sender can hide an attachment from a filter that relies on ambiguous_content() while the recipient's mail client shows it.

Severity

Not scored

CVSS score

Not available

Vulnerability status

Awaiting Analysis

Source identifier

9b29abf9-4ab0-4765-b253-1875cd9b441e

Published

2026-10-28 18:17:13.017000

Last modified

2026-10-29 15:11:53

View original CVE JSON

{
  "id": "CVE-2026-116266",
  "sourceIdentifier": "9b29abf9-4ab0-4765-b253-1875cd9b441e",
  "published": "2026-10-28T18:17:13.017",
  "lastModified": "2026-10-29T15:11:53.000",
  "vulnStatus": "Awaiting Analysis",
  "cveTags": [],
  "descriptions": [
    {
      "lang": "en",
      "value": "MIME::Head versions from 5.518 before 5.521 for Perl decode a partly encoded multipart boundary without flagging the parse as ambiguous.\n\nThe multipart_boundary() method decodes RFC 2047 encoded words anywhere in the boundary, but the ambiguity check only fires when the whole value is one encoded word. A boundary such as abc=?us-ascii?Q?def?= is used as abcdef, and ambiguous_content() returns false.\n\nEncoded words are not allowed in parameters, so other mail readers split the message on the literal value. A remote sender can hide an attachment from a filter that relies on ambiguous_content() while the recipient's mail client shows it."
    }
  ],
  "affected": [
    {
      "source": "9b29abf9-4ab0-4765-b253-1875cd9b441e",
      "affectedData": [
        {
          "defaultStatus": "unaffected",
          "collectionURL": "https://cpan.org/modules",
          "packageName": "MIME-tools",
          "modules": [
            "MIME::Head"
          ],
          "programFiles": [
            "lib/MIME/Head.pm",
            "lib/MIME/Field/ParamVal.pm"
          ],
          "programRoutines": [
            {
              "name": "MIME::Head::multipart_boundary"
            },
            {
              "name": "MIME::Field::ParamVal::parse_params"
            }
          ],
          "repo": "https://salsa.debian.org/dskoll/mime-tools",
          "packageURL": "pkg:cpan/MIME-tools",
          "versions": [
            {
              "version": "5.518",
              "lessThan": "5.521",
              "versionType": "custom",
              "status": "affected"
            }
          ]
        }
      ]
    }
  ],
  "metrics": {},
  "weaknesses": [
    {
      "source": "9b29abf9-4ab0-4765-b253-1875cd9b441e",
      "type": "Secondary",
      "description": [
        {
          "lang": "en",
          "value": "CWE-436"
        }
      ]
    }
  ],
  "references": [
    {
      "url": "https://metacpan.org/release/DSKOLL/MIME-tools-5.521/changes",
      "source": "9b29abf9-4ab0-4765-b253-1875cd9b441e"
    }
  ]
}