CVE-2026-40561

{
  "id": "CVE-2026-40561",
  "sourceIdentifier": "9b29abf9-4ab0-4765-b253-1875cd9b441e",
  "published": "2026-05-03T01:15:58.390",
  "lastModified": "2026-10-26T20:10:00.160",
  "vulnStatus": "Modified",
  "cveTags": [],
  "descriptions": [
    {
      "lang": "en",
      "value": "Starlet versions through 0.31 for Perl allows HTTP Request Smuggling via Improper Header Precedence.\n\nStarlet incorrectly prioritizes \"Content-Length\" over \"Transfer-Encoding: chunked\" when both headers are present in an HTTP request. Per RFC 7230 3.3.3, Transfer-Encoding must take precedence.\n\nAn attacker could exploit this to smuggle malicious HTTP requests via a front-end reverse proxy."
    },
    {
      "lang": "es",
      "value": "Las versiones de Starlet hasta la 0.31 para Perl permiten el Contrabando de Solicitudes HTTP a través de una Precedencia de Encabezado Inadecuada.\n\nStarlet prioriza incorrectamente ’Content-Length’ sobre ’Transfer-Encoding: chunked’ cuando ambos encabezados están presentes en una solicitud HTTP. Según la RFC 7230 3.3.3, Transfer-Encoding debe tener precedencia.\n\nUn atacante podría explotar esto para contrabandear solicitudes HTTP maliciosas a través de un proxy inverso de front-end."
    }
  ],
  "affected": [
    {
      "source": "9b29abf9-4ab0-4765-b253-1875cd9b441e",
      "affectedData": [
        {
          "vendor": "KAZUHO",
          "product": "Starlet",
          "defaultStatus": "unaffected",
          "collectionURL": "https://cpan.org/modules",
          "packageName": "Starlet",
          "programFiles": [
            "lib/Starlet/Server.pm"
          ],
          "programRoutines": [
            {
              "name": "Starlet::Server::handle_connection"
            }
          ],
          "repo": "https://github.com/kazuho/Starlet",
          "versions": [
            {
              "version": "0",
              "lessThanOrEqual": "0.31",
              "versionType": "custom",
              "status": "affected"
            }
          ]
        }
      ]
    }
  ],
  "metrics": {
    "cvssMetricV31": [
      {
        "source": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
        "type": "Secondary",
        "cvssData": {
          "version": "3.1",
          "vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N",
          "baseScore": 5.3,
          "baseSeverity": "MEDIUM",
          "attackVector": "NETWORK",
          "attackComplexity": "LOW",
          "privilegesRequired": "NONE",
          "userInteraction": "NONE",
          "scope": "UNCHANGED",
          "confidentialityImpact": "NONE",
          "integrityImpact": "LOW",
          "availabilityImpact": "NONE"
        },
        "exploitabilityScore": 3.9,
        "impactScore": 1.4
      }
    ],
    "ssvcV203": [
      {
        "source": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
        "ssvcData": {
          "timestamp": "2026-05-04T13:54:42.679845Z",
          "id": "CVE-2026-40561",
          "options": [
            {
              "exploitation": "none"
            },
            {
              "automatable": "yes"
            },
            {
              "technicalImpact": "partial"
            }
          ],
          "role": "CISA Coordinator",
          "version": "2.0.3"
        }
      }
    ]
  },
  "weaknesses": [
    {
      "source": "9b29abf9-4ab0-4765-b253-1875cd9b441e",
      "type": "Secondary",
      "description": [
        {
          "lang": "en",
          "value": "CWE-444"
        }
      ]
    }
  ],
  "configurations": [
    {
      "nodes": [
        {
          "operator": "OR",
          "negate": false,
          "cpeMatch": [
            {
              "vulnerable": true,
              "criteria": "cpe:2.3:a:kazuho:starlet:*:*:*:*:*:perl:*:*",
              "versionEndIncluding": "0.31",
              "matchCriteriaId": "D7E737B0-BC8D-4FDA-A6B2-E36FC466209A"
            }
          ]
        }
      ]
    }
  ],
  "references": [
    {
      "url": "https://datatracker.ietf.org/doc/html/rfc7230#section-3.3.3",
      "source": "9b29abf9-4ab0-4765-b253-1875cd9b441e",
      "tags": [
        "Third Party Advisory"
      ]
    },
    {
      "url": "https://github.com/kazuho/Starlet/commit/a7d5dfd1862aafa43e5eaca0fdb6acf4cc15b2d0.patch",
      "source": "9b29abf9-4ab0-4765-b253-1875cd9b441e",
      "tags": [
        "Patch"
      ]
    },
    {
      "url": "https://metacpan.org/release/KAZUHO/Starlet-0.32/changes",
      "source": "9b29abf9-4ab0-4765-b253-1875cd9b441e"
    },
    {
      "url": "http://www.openwall.com/lists/oss-security/2026/05/03/1",
      "source": "af854a3a-2127-422b-91ae-364da2661108",
      "tags": [
        "Mailing List",
        "Third Party Advisory"
      ]
    }
  ]
}