NCSC-2026-0171

Vulnerability from csaf_ncscnl - Published: 2026-05-29 19:08 - Updated: 2026-05-29 19:08
Summary
Kwetsbaarheid verholpen in Starlette
Notes
The Netherlands Cyber Security Center (henceforth: NCSC-NL) maintains this page to enhance access to its information and security advisories. The use of this security advisory is subject to the following terms and conditions: NCSC-NL makes every reasonable effort to ensure that the content of this page is kept up to date, and that it is accurate and complete. Nevertheless, NCSC-NL cannot entirely rule out the possibility of errors, and therefore cannot give any warranty in respect of its completeness, accuracy or continuous keeping up-to-date. The information contained in this security advisory is intended solely for the purpose of providing general information to professional users. No rights can be derived from the information provided therein. NCSC-NL and the Kingdom of the Netherlands assume no legal liability or responsibility for any damage resulting from either the use or inability of use of this security advisory. This includes damage resulting from the inaccuracy of incompleteness of the information contained in the advisory. This security advisory is subject to Dutch law. All disputes related to or arising from the use of this advisory will be submitted to the competent court in The Hague. This choice of means also applies to the court in summary proceedings.
Feiten: Er is een kwetsbaarheid verholpen in Starlette, een Python-library voor het ontwikkelen van webservices. Starlette wordt door verschillende producten gebruikt, waaronder FastAPI.
Interpretaties: Een ongeauthenticeerde kwaadwillende kan de kwetsbaarheid misbruiken voor het omzeilen van authenticatie. Hierdoor kan de kwaadwillende afgeschermde URL-paden benaderen. Zodoende krijgt de kwaadwillende ongeauthenticeerde toegang tot functionaliteiten of data van een webservice die een kwetsbare Starlette-versie gebruikt. De kwetsbaarheid wordt veroorzaakt doordat het pad in de Host-header onvoldoende wordt geverifieerd. De mogelijke impact van misbruik is afhankelijk van het soort data dat door een kwetsbare webservice wordt verwerkt en de functionaliteiten die deze service biedt.
Oplossingen: De kwetsbaarheid is verholpen in Starlette versie 1.0.1. Applicaties die Startelle gebruiken, dienen Starlette bij te werken naar deze of een latere versie. Indien jouw organisatie applicaties gebruikt waar Starlette onderdeel van is, zoals FastAPI, dan ben je voor beveiligingsupdates mogelijk afhankelijk van je leverancier. Wanneer een van je applicaties een kwetsbare versie van Starlette gebruikt en het niet mogelijk is om Starlette te updaten, kan de kans op misbruik worden beperkt door de kwetsbare applicatie niet naar het internet te ontsluiten of authenticatie via een reverse proxy in te regelen. Lees de bijgevoegde referenties voor meer informatie.
Kans: high
Schade: medium
CWE-444: Inconsistent Interpretation of HTTP Requests ('HTTP Request/Response Smuggling')
CVE-2026-48710

Starlette versions before 1.0.1 did not validate the HTTP Host header when reconstructing request URLs, allowing attackers to inject paths and potentially bypass authentication based on the reconstructed URL path.

6.5 (Medium)
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:N
CWE-444 - Inconsistent Interpretation of HTTP Requests ('HTTP Request/Response Smuggling')
Affected products
Product Identifier Version Remediation
vers:unknown/*
Kludex / starlette
 vers:unknown/*
References
To clipboard 

{
  "document": {
    "category": "csaf_security_advisory",
    "csaf_version": "2.0",
    "distribution": {
      "tlp": {
        "label": "WHITE"
      }
    },
    "lang": "nl",
    "notes": [
      {
        "category": "legal_disclaimer",
        "text": "The Netherlands Cyber Security Center (henceforth: NCSC-NL) maintains this page to enhance access to its information and security advisories. The use of this security advisory is subject to the following terms and conditions:\n\n    NCSC-NL makes every reasonable effort to ensure that the content of this page is kept up to date, and that it is accurate and complete. Nevertheless, NCSC-NL cannot entirely rule out the possibility of errors, and therefore cannot give any warranty in respect of its completeness, accuracy or continuous keeping up-to-date. The information contained in this security advisory is intended solely for the purpose of providing general information to professional users. No rights can be derived from the information provided therein.\n\n    NCSC-NL and the Kingdom of the Netherlands assume no legal liability or responsibility for any damage resulting from either the use or inability of use of this security advisory. This includes damage resulting from the inaccuracy of incompleteness of the information contained in the advisory.\n    This security advisory is subject to Dutch law. All disputes related to or arising from the use of this advisory will be submitted to the competent court in The Hague. This choice of means also applies to the court in summary proceedings."
      },
      {
        "category": "description",
        "text": "Er is een kwetsbaarheid verholpen in Starlette, een Python-library voor het ontwikkelen van webservices. Starlette wordt door verschillende producten gebruikt, waaronder FastAPI.",
        "title": "Feiten"
      },
      {
        "category": "description",
        "text": "Een ongeauthenticeerde kwaadwillende kan de kwetsbaarheid misbruiken voor het omzeilen van authenticatie. Hierdoor kan de kwaadwillende afgeschermde URL-paden benaderen. Zodoende krijgt de kwaadwillende ongeauthenticeerde toegang tot functionaliteiten of data van een webservice die een kwetsbare Starlette-versie gebruikt.\n\nDe kwetsbaarheid wordt veroorzaakt doordat het pad in de Host-header onvoldoende wordt geverifieerd. De mogelijke impact van misbruik is afhankelijk van het soort data dat door een kwetsbare webservice wordt verwerkt en de functionaliteiten die deze service biedt.",
        "title": "Interpretaties"
      },
      {
        "category": "description",
        "text": "De kwetsbaarheid is verholpen in Starlette versie 1.0.1. Applicaties die Startelle gebruiken, dienen Starlette bij te werken naar deze of een latere versie.\n\nIndien jouw organisatie applicaties gebruikt waar Starlette onderdeel van is, zoals FastAPI, dan ben je voor beveiligingsupdates mogelijk afhankelijk van je leverancier.\n\nWanneer een van je applicaties een kwetsbare versie van Starlette gebruikt en het niet mogelijk is om Starlette te updaten, kan de kans op misbruik worden beperkt door de kwetsbare applicatie niet naar het internet te ontsluiten of authenticatie via een reverse proxy in te regelen.\n\nLees de bijgevoegde referenties voor meer informatie.",
        "title": "Oplossingen"
      },
      {
        "category": "general",
        "text": "high",
        "title": "Kans"
      },
      {
        "category": "general",
        "text": "medium",
        "title": "Schade"
      },
      {
        "category": "general",
        "text": "Inconsistent Interpretation of HTTP Requests (\u0027HTTP Request/Response Smuggling\u0027)",
        "title": "CWE-444"
      }
    ],
    "publisher": {
      "category": "coordinator",
      "contact_details": "cert@ncsc.nl",
      "name": "Nationaal Cyber Security Centrum",
      "namespace": "https://www.ncsc.nl/"
    },
    "references": [
      {
        "category": "external",
        "summary": "Reference",
        "url": "https://badhost.org/"
      },
      {
        "category": "external",
        "summary": "Reference",
        "url": "https://github.com/Kludex/starlette/security/advisories/GHSA-86qp-5c8j-p5mr"
      }
    ],
    "title": "Kwetsbaarheid verholpen in Starlette",
    "tracking": {
      "current_release_date": "2026-05-29T19:08:23.623424Z",
      "generator": {
        "date": "2025-08-04T16:30:00Z",
        "engine": {
          "name": "V.A.",
          "version": "1.3"
        }
      },
      "id": "NCSC-2026-0171",
      "initial_release_date": "2026-05-29T19:08:23.623424Z",
      "revision_history": [
        {
          "date": "2026-05-29T19:08:23.623424Z",
          "number": "1.0.0",
          "summary": "Initiele versie"
        }
      ],
      "status": "final",
      "version": "1.0.0"
    }
  },
  "product_tree": {
    "branches": [
      {
        "branches": [
          {
            "branches": [
              {
                "category": "product_version_range",
                "name": "vers:unknown/*",
                "product": {
                  "name": "vers:unknown/*",
                  "product_id": "CSAFPID-1"
                }
              }
            ],
            "category": "product_name",
            "name": "starlette"
          }
        ],
        "category": "vendor",
        "name": "Kludex"
      }
    ]
  },
  "vulnerabilities": [
    {
      "cve": "CVE-2026-48710",
      "cwe": {
        "id": "CWE-444",
        "name": "Inconsistent Interpretation of HTTP Requests (\u0027HTTP Request/Response Smuggling\u0027)"
      },
      "notes": [
        {
          "category": "other",
          "text": "Inconsistent Interpretation of HTTP Requests (\u0027HTTP Request/Response Smuggling\u0027)",
          "title": "CWE-444"
        },
        {
          "category": "description",
          "text": "Starlette versions before 1.0.1 did not validate the HTTP Host header when reconstructing request URLs, allowing attackers to inject paths and potentially bypass authentication based on the reconstructed URL path.",
          "title": "Summary"
        }
      ],
      "product_status": {
        "known_affected": [
          "CSAFPID-1"
        ]
      },
      "references": [
        {
          "category": "self",
          "summary": "CVE-2026-48710 | NCSC-NL Website",
          "url": "https://vulnerabilities.ncsc.nl/csaf/v2/2026/cve-2026-48710.json"
        }
      ],
      "scores": [
        {
          "cvss_v3": {
            "baseScore": 6.5,
            "baseSeverity": "MEDIUM",
            "vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:N",
            "version": "3.1"
          },
          "products": [
            "CSAFPID-1"
          ]
        }
      ],
      "title": "CVE-2026-48710"
    }
  ]
}



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