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starlette — security advisory

Type: advisorySources: OSVAdvisory ID: DEBIAN-CVE-2025-62727

Starlette is a lightweight ASGI framework/toolkit. Starting in version 0.39.0 and prior to version 0.49.1 , an unauthenticated attacker can send a crafted HTTP Range header that triggers quadratic-time processing in Starlette's FileResponse Range parsing/merging logic. This enables CPU exhaustion per request, causing denial‑of‑service for endpoints serving files (e.g., StaticFiles or any use of FileResponse). This vulnerability is fixed in 0.49.1.

Products
starlette
Affected versions
0.46.1-3
Fixed versions
0.46.1-3+deb13u1, 0.50.0-1
CVEs
CVE-2025-62727
Confirmed fixed CVEs
Not specified
Updated in this feed
28 Oct 2026, 11:06 UTC · Revision 1

Source evidence

DEBIAN-CVE-2025-62727

core-osv · Original source

Published 28 Oct 2025, 21:15 UTC

Starlette is a lightweight ASGI framework/toolkit. Starting in version 0.39.0 and prior to version 0.49.1 , an unauthenticated attacker can send a crafted HTTP Range header that triggers quadratic-time processing in Starlette's FileResponse Range parsing/merging logic. This enables CPU exhaustion per request, causing denial‑of‑service for endpoints serving files (e.g., StaticFiles or any use of FileResponse). This vulnerability is fixed in 0.49.1.

osv:DEBIAN-CVE-2025-62727

starlette

Fixed versions: 0.46.1-3+deb13u1

starlette

Fixed versions: 0.50.0-1

Complete source record
{
  "id": "7bd900270fb3be22dd1bb5e7f2734e2e48d151bb4df678ebc690c676c350dc4d",
  "url": "https://osv.dev/vulnerability/DEBIAN-CVE-2025-62727",
  "method": "structured",
  "payload": {
    "kind": "advisory",
    "title": "DEBIAN-CVE-2025-62727",
    "summary": "Starlette is a lightweight ASGI framework/toolkit. Starting in version 0.39.0 and prior to version 0.49.1 , an unauthenticated attacker can send a crafted HTTP Range header that triggers quadratic-time processing in Starlette's FileResponse Range parsing/merging logic. This enables CPU exhaustion per request, causing denial‑of‑service for endpoints serving files (e.g., StaticFiles or any use of FileResponse). This vulnerability is fixed in 0.49.1.",
    "evidence": "osv:DEBIAN-CVE-2025-62727",
    "products": [
      {
        "name": {
          "value": "starlette",
          "evidence": "/affected/0/package/name"
        },
        "prerequisites": [],
        "fixed_versions": [
          {
            "value": "0.46.1-3+deb13u1",
            "evidence": "/affected/0/ranges"
          }
        ],
        "affected_versions": [
          {
            "value": "0.46.1-3",
            "evidence": "/affected/0/versions"
          }
        ]
      },
      {
        "name": {
          "value": "starlette",
          "evidence": "/affected/1/package/name"
        },
        "prerequisites": [],
        "fixed_versions": [
          {
            "value": "0.50.0-1",
            "evidence": "/affected/1/ranges"
          }
        ],
        "affected_versions": [
          {
            "value": "0.46.1-3",
            "evidence": "/affected/1/versions"
          }
        ]
      }
    ],
    "severity": "high",
    "structured": {
      "id": "DEBIAN-CVE-2025-62727",
      "aliases": [
        "DEBIAN-CVE-2025-62727"
      ],
      "metrics": [
        {
          "type": "CVSS_V3",
          "score": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H"
        }
      ],
      "affected": [
        {
          "ranges": [
            {
              "type": "ECOSYSTEM",
              "events": [
                {
                  "introduced": "0"
                },
                {
                  "fixed": "0.46.1-3+deb13u1"
                }
              ]
            }
          ],
          "package": {
            "name": "starlette",
            "purl": "pkg:deb/debian/starlette?arch=source&distro=trixie",
            "ecosystem": "Debian:13"
          },
          "versions": [
            "0.46.1-3"
          ],
          "database_specific": {
            "source": "https://storage.googleapis.com/debian-osv/debian-cve-osv/DEBIAN-CVE-2025-62727.json"
          },
          "ecosystem_specific": {
            "urgency": "not yet assigned"
          }
        },
        {
          "ranges": [
            {
              "type": "ECOSYSTEM",
              "events": [
                {
                  "introduced": "0"
                },
                {
                  "fixed": "0.50.0-1"
                }
              ]
            }
          ],
          "package": {
            "name": "starlette",
            "purl": "pkg:deb/debian/starlette?arch=source&distro=forky",
            "ecosystem": "Debian:14"
          },
          "versions": [
            "0.46.1-3"
          ],
          "database_specific": {
            "source": "https://storage.googleapis.com/debian-osv/debian-cve-osv/DEBIAN-CVE-2025-62727.json"
          },
          "ecosystem_specific": {
            "urgency": "not yet assigned"
          }
        }
      ],
      "modified": "2026-10-09T09:47:24.031480346Z",
      "provider": "osv",
      "upstream": [
        "CVE-2025-62727"
      ],
      "references": [
        "https://security-tracker.debian.org/tracker/CVE-2025-62727"
      ]
    },
    "related_cves": [
      {
        "value": "CVE-2025-62727",
        "evidence": "/upstream"
      }
    ],
    "security_relevant": true,
    "severity_evidence": "/severity/0/score"
  },
  "source_id": "core-osv",
  "document_id": 111450,
  "published_at": "2025-10-28T21:15:40.447+00:00"
}