CVE-2026-116266 (GCVE-0-2026-116266)

Vulnerability from cvelistv5 – Published: 2026-10-28 17:32 – Updated: 2026-10-28 17:32
VLAI
Title
MIME::Head versions from 5.518 before 5.521 for Perl decode a partly encoded multipart boundary without flagging the parse as ambiguous
Summary
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
No CVSS data available.
CWE
  • CWE-436 - Interpretation Conflict
Assigner
CPANSec CNA under the redhat root
CNA scorecard C 63/100 over 317 records in the last 180 days details
References
Impacted products
Vendor Product Version CPE status
Affected: 5.518 , < 5.521 (custom)
Show details on NVD website
To clipboard 

{
  "containers": {
    "cna": {
      "affected": [
        {
          "collectionURL": "https://cpan.org/modules",
          "defaultStatus": "unaffected",
          "modules": [
            "MIME::Head"
          ],
          "packageName": "MIME-tools",
          "packageURL": "pkg:cpan/MIME-tools",
          "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",
          "versions": [
            {
              "lessThan": "5.521",
              "status": "affected",
              "version": "5.518",
              "versionType": "custom"
            }
          ]
        }
      ],
      "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\u0027s mail client shows it."
        }
      ],
      "problemTypes": [
        {
          "descriptions": [
            {
              "cweId": "CWE-436",
              "description": "CWE-436 Interpretation Conflict",
              "lang": "en",
              "type": "CWE"
            }
          ]
        }
      ],
      "providerMetadata": {
        "dateUpdated": "2026-10-28T17:32:28.565Z",
        "orgId": "9b29abf9-4ab0-4765-b253-1875cd9b441e",
        "shortName": "CPANSec"
      },
      "references": [
        {
          "tags": [
            "release-notes"
          ],
          "url": "https://metacpan.org/release/DSKOLL/MIME-tools-5.521/changes"
        }
      ],
      "solutions": [
        {
          "lang": "en",
          "value": "Upgrade to MIME-tools 5.521 or later."
        }
      ],
      "source": {
        "discovery": "UNKNOWN"
      },
      "title": "MIME::Head versions from 5.518 before 5.521 for Perl decode a partly encoded multipart boundary without flagging the parse as ambiguous",
      "x_generator": {
        "engine": "cpansec-cna-tool 0.1"
      }
    }
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  "cveMetadata": {
    "assignerOrgId": "9b29abf9-4ab0-4765-b253-1875cd9b441e",
    "assignerShortName": "CPANSec",
    "cveId": "CVE-2026-116266",
    "datePublished": "2026-10-28T17:32:28.565Z",
    "dateReserved": "2026-10-25T18:05:02.235Z",
    "dateUpdated": "2026-10-28T17:32:28.565Z",
    "state": "PUBLISHED"
  },
  "dataType": "CVE_RECORD",
  "dataVersion": "5.2",
  "vulnerability-lookup:meta": {
    "epss": {
      "cve": "CVE-2026-116266",
      "date": "2026-10-29",
      "epss": "0.00177",
      "percentile": "0.07255"
    },
    "nvd": {
      "cve": {
        "affected": [
          {
            "affectedData": [
              {
                "collectionURL": "https://cpan.org/modules",
                "defaultStatus": "unaffected",
                "modules": [
                  "MIME::Head"
                ],
                "packageName": "MIME-tools",
                "packageURL": "pkg:cpan/MIME-tools",
                "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",
                "versions": [
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                    "lessThan": "5.521",
                    "status": "affected",
                    "version": "5.518",
                    "versionType": "custom"
                  }
                ]
              }
            ],
            "source": "9b29abf9-4ab0-4765-b253-1875cd9b441e"
          }
        ],
        "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\u0027s mail client shows it."
          }
        ],
        "id": "CVE-2026-116266",
        "lastModified": "2026-10-29T15:11:53.000",
        "metrics": {},
        "published": "2026-10-28T18:17:13.017",
        "references": [
          {
            "source": "9b29abf9-4ab0-4765-b253-1875cd9b441e",
            "url": "https://metacpan.org/release/DSKOLL/MIME-tools-5.521/changes"
          }
        ],
        "sourceIdentifier": "9b29abf9-4ab0-4765-b253-1875cd9b441e",
        "vulnStatus": "Awaiting Analysis",
        "weaknesses": [
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            "description": [
              {
                "lang": "en",
                "value": "CWE-436"
              }
            ],
            "source": "9b29abf9-4ab0-4765-b253-1875cd9b441e",
            "type": "Secondary"
          }
        ]
      }
    }
  }
}



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