GCVE Workshop - 22 September 2026 (14:00-18:00), Luxembourg Before The Vulnopticon Conference - Registration

CVE-2025-62727 (GCVE-0-2025-62727)

Vulnerability from cvelistv5 – Published: 2025-10-28 20:14 – Updated: 2025-11-04 17:41
VLAI
Title
Starlette vulnerable to O(n^2) DoS via Range header merging in starlette.responses.FileResponse
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.
Severity
7.5 (High)
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
SSVC
Exploitation: poc Automatable: yes Technical Impact: partial
CISA Coordinator · CISA-ADP (v2.0.3)
Decision recorded 2025-10-28 20:36 UTC
CWE
  • CWE-407 - Inefficient Algorithmic Complexity
Assigner
References
Impacted products
Vendor Product Version CPE status
Kludex starlette Affected: >= 0.39.0, < 0.49.1
guessed Create a notification for this product.
Show details on NVD website
To clipboard 

{
  "containers": {
    "adp": [
      {
        "metrics": [
          {
            "other": {
              "content": {
                "id": "CVE-2025-62727",
                "options": [
                  {
                    "Exploitation": "poc"
                  },
                  {
                    "Automatable": "yes"
                  },
                  {
                    "Technical Impact": "partial"
                  }
                ],
                "role": "CISA Coordinator",
                "timestamp": "2025-10-28T20:36:34.130234Z",
                "version": "2.0.3"
              },
              "type": "ssvc"
            }
          }
        ],
        "providerMetadata": {
          "dateUpdated": "2025-10-28T20:36:49.189Z",
          "orgId": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
          "shortName": "CISA-ADP"
        },
        "references": [
          {
            "tags": [
              "exploit"
            ],
            "url": "https://github.com/Kludex/starlette/security/advisories/GHSA-7f5h-v6xp-fcq8"
          }
        ],
        "title": "CISA ADP Vulnrichment"
      }
    ],
    "cna": {
      "affected": [
        {
          "product": "starlette",
          "vendor": "Kludex",
          "versions": [
            {
              "status": "affected",
              "version": "\u003e= 0.39.0, \u003c 0.49.1"
            }
          ]
        }
      ],
      "descriptions": [
        {
          "lang": "en",
          "value": "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\u0027s FileResponse Range parsing/merging logic. This enables CPU exhaustion per request, causing denial\u2011of\u2011service for endpoints serving files (e.g., StaticFiles or any use of FileResponse). This vulnerability is fixed in 0.49.1."
        }
      ],
      "metrics": [
        {
          "cvssV3_1": {
            "attackComplexity": "LOW",
            "attackVector": "NETWORK",
            "availabilityImpact": "HIGH",
            "baseScore": 7.5,
            "baseSeverity": "HIGH",
            "confidentialityImpact": "NONE",
            "integrityImpact": "NONE",
            "privilegesRequired": "NONE",
            "scope": "UNCHANGED",
            "userInteraction": "NONE",
            "vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H",
            "version": "3.1"
          }
        }
      ],
      "problemTypes": [
        {
          "descriptions": [
            {
              "cweId": "CWE-407",
              "description": "CWE-407: Inefficient Algorithmic Complexity",
              "lang": "en",
              "type": "CWE"
            }
          ]
        }
      ],
      "providerMetadata": {
        "dateUpdated": "2025-11-04T17:41:42.316Z",
        "orgId": "a0819718-46f1-4df5-94e2-005712e83aaa",
        "shortName": "GitHub_M"
      },
      "references": [
        {
          "name": "https://github.com/Kludex/starlette/security/advisories/GHSA-7f5h-v6xp-fcq8",
          "tags": [
            "x_refsource_CONFIRM"
          ],
          "url": "https://github.com/Kludex/starlette/security/advisories/GHSA-7f5h-v6xp-fcq8"
        },
        {
          "name": "https://github.com/Kludex/starlette/commit/4ea6e22b489ec388d6004cfbca52dd5b147127c5",
          "tags": [
            "x_refsource_MISC"
          ],
          "url": "https://github.com/Kludex/starlette/commit/4ea6e22b489ec388d6004cfbca52dd5b147127c5"
        },
        {
          "name": "https://github.com/Kludex/starlette/commit/69ed26a85956ef4bd0161807eb27abf49be7cd3c",
          "tags": [
            "x_refsource_MISC"
          ],
          "url": "https://github.com/Kludex/starlette/commit/69ed26a85956ef4bd0161807eb27abf49be7cd3c"
        },
        {
          "name": "https://github.com/Kludex/starlette/releases/tag/0.49.1",
          "tags": [
            "x_refsource_MISC"
          ],
          "url": "https://github.com/Kludex/starlette/releases/tag/0.49.1"
        }
      ],
      "source": {
        "advisory": "GHSA-7f5h-v6xp-fcq8",
        "discovery": "UNKNOWN"
      },
      "title": "Starlette vulnerable to O(n^2) DoS via Range header merging in starlette.responses.FileResponse"
    }
  },
  "cveMetadata": {
    "assignerOrgId": "a0819718-46f1-4df5-94e2-005712e83aaa",
    "assignerShortName": "GitHub_M",
    "cveId": "CVE-2025-62727",
    "datePublished": "2025-10-28T20:14:53.655Z",
    "dateReserved": "2025-10-20T19:41:22.742Z",
    "dateUpdated": "2025-11-04T17:41:42.316Z",
    "state": "PUBLISHED"
  },
  "dataType": "CVE_RECORD",
  "dataVersion": "5.2",
  "vulnerability-lookup:meta": {
    "epss": {
      "cve": "CVE-2025-62727",
      "date": "2026-09-06",
      "epss": "0.00638",
      "percentile": "0.48311"
    },
    "nvd": "{\"cve\":{\"id\":\"CVE-2025-62727\",\"sourceIdentifier\":\"security-advisories@github.com\",\"published\":\"2025-10-28T21:15:40.447\",\"lastModified\":\"2026-06-17T09:52:20.480\",\"vulnStatus\":\"Deferred\",\"cveTags\":[],\"descriptions\":[{\"lang\":\"en\",\"value\":\"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\u0027s FileResponse Range parsing/merging logic. This enables CPU exhaustion per request, causing denial\u2011of\u2011service for endpoints serving files (e.g., StaticFiles or any use of FileResponse). This vulnerability is fixed in 0.49.1.\"}],\"affected\":[{\"source\":\"security-advisories@github.com\",\"affectedData\":[{\"vendor\":\"Kludex\",\"product\":\"starlette\",\"versions\":[{\"version\":\"\u003e= 0.39.0, \u003c 0.49.1\",\"status\":\"affected\"}]}]}],\"metrics\":{\"cvssMetricV31\":[{\"source\":\"security-advisories@github.com\",\"type\":\"Secondary\",\"cvssData\":{\"version\":\"3.1\",\"vectorString\":\"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H\",\"baseScore\":7.5,\"baseSeverity\":\"HIGH\",\"attackVector\":\"NETWORK\",\"attackComplexity\":\"LOW\",\"privilegesRequired\":\"NONE\",\"userInteraction\":\"NONE\",\"scope\":\"UNCHANGED\",\"confidentialityImpact\":\"NONE\",\"integrityImpact\":\"NONE\",\"availabilityImpact\":\"HIGH\"},\"exploitabilityScore\":3.9,\"impactScore\":3.6}],\"ssvcV203\":[{\"source\":\"134c704f-9b21-4f2e-91b3-4a467353bcc0\",\"ssvcData\":{\"timestamp\":\"2025-10-28T20:36:34.130234Z\",\"id\":\"CVE-2025-62727\",\"options\":[{\"exploitation\":\"poc\"},{\"automatable\":\"yes\"},{\"technicalImpact\":\"partial\"}],\"role\":\"CISA Coordinator\",\"version\":\"2.0.3\"}}]},\"weaknesses\":[{\"source\":\"security-advisories@github.com\",\"type\":\"Secondary\",\"description\":[{\"lang\":\"en\",\"value\":\"CWE-407\"}]}],\"references\":[{\"url\":\"https://github.com/Kludex/starlette/commit/4ea6e22b489ec388d6004cfbca52dd5b147127c5\",\"source\":\"security-advisories@github.com\"},{\"url\":\"https://github.com/Kludex/starlette/commit/69ed26a85956ef4bd0161807eb27abf49be7cd3c\",\"source\":\"security-advisories@github.com\"},{\"url\":\"https://github.com/Kludex/starlette/releases/tag/0.49.1\",\"source\":\"security-advisories@github.com\"},{\"url\":\"https://github.com/Kludex/starlette/security/advisories/GHSA-7f5h-v6xp-fcq8\",\"source\":\"security-advisories@github.com\"},{\"url\":\"https://github.com/Kludex/starlette/security/advisories/GHSA-7f5h-v6xp-fcq8\",\"source\":\"134c704f-9b21-4f2e-91b3-4a467353bcc0\"}]}}",
    "redhat_vex": {
      "aggregate_severity": "Important",
      "current_release_date": "2026-08-21T20:23:04+00:00",
      "cve": "CVE-2025-62727",
      "id": "CVE-2025-62727",
      "initial_release_date": "2025-10-28T20:14:53.655000+00:00",
      "product_status:fixed": "85",
      "product_status:known_affected": "17",
      "product_status:known_not_affected": "423",
      "source": "Red Hat CSAF VEX",
      "status": "final",
      "title": "starlette: Starlette DoS via Range header merging",
      "url": "https://security.access.redhat.com/data/csaf/v2/vex/2025/cve-2025-62727.json",
      "version": "3"
    },
    "suse_vex": {
      "aggregate_severity": "important",
      "current_release_date": "2026-07-16T18:12:02Z",
      "cve": "CVE-2025-62727",
      "id": "CVE-2025-62727",
      "initial_release_date": "2025-10-30T00:23:37Z",
      "product_status:known_not_affected": "2",
      "product_status:recommended": "10",
      "source": "SUSE CSAF VEX",
      "status": "interim",
      "title": "SUSE CVE CVE-2025-62727",
      "url": "https://ftp.suse.com/pub/projects/security/csaf-vex/cve-2025-62727.json",
      "version": "11"
    },
    "vulnrichment": {
      "containers": "{\"adp\": [{\"title\": \"CISA ADP Vulnrichment\", \"metrics\": [{\"other\": {\"type\": \"ssvc\", \"content\": {\"id\": \"CVE-2025-62727\", \"role\": \"CISA Coordinator\", \"options\": [{\"Exploitation\": \"poc\"}, {\"Automatable\": \"yes\"}, {\"Technical Impact\": \"partial\"}], \"version\": \"2.0.3\", \"timestamp\": \"2025-10-28T20:36:34.130234Z\"}}}], \"references\": [{\"url\": \"https://github.com/Kludex/starlette/security/advisories/GHSA-7f5h-v6xp-fcq8\", \"tags\": [\"exploit\"]}], \"providerMetadata\": {\"orgId\": \"134c704f-9b21-4f2e-91b3-4a467353bcc0\", \"shortName\": \"CISA-ADP\", \"dateUpdated\": \"2025-10-28T20:36:44.968Z\"}}], \"cna\": {\"title\": \"Starlette vulnerable to O(n^2) DoS via Range header merging in starlette.responses.FileResponse\", \"source\": {\"advisory\": \"GHSA-7f5h-v6xp-fcq8\", \"discovery\": \"UNKNOWN\"}, \"metrics\": [{\"cvssV3_1\": {\"scope\": \"UNCHANGED\", \"version\": \"3.1\", \"baseScore\": 7.5, \"attackVector\": \"NETWORK\", \"baseSeverity\": \"HIGH\", \"vectorString\": \"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H\", \"integrityImpact\": \"NONE\", \"userInteraction\": \"NONE\", \"attackComplexity\": \"LOW\", \"availabilityImpact\": \"HIGH\", \"privilegesRequired\": \"NONE\", \"confidentialityImpact\": \"NONE\"}}], \"affected\": [{\"vendor\": \"Kludex\", \"product\": \"starlette\", \"versions\": [{\"status\": \"affected\", \"version\": \"\u003e= 0.39.0, \u003c 0.49.1\"}]}], \"references\": [{\"url\": \"https://github.com/Kludex/starlette/security/advisories/GHSA-7f5h-v6xp-fcq8\", \"name\": \"https://github.com/Kludex/starlette/security/advisories/GHSA-7f5h-v6xp-fcq8\", \"tags\": [\"x_refsource_CONFIRM\"]}, {\"url\": \"https://github.com/Kludex/starlette/commit/4ea6e22b489ec388d6004cfbca52dd5b147127c5\", \"name\": \"https://github.com/Kludex/starlette/commit/4ea6e22b489ec388d6004cfbca52dd5b147127c5\", \"tags\": [\"x_refsource_MISC\"]}, {\"url\": \"https://github.com/Kludex/starlette/commit/69ed26a85956ef4bd0161807eb27abf49be7cd3c\", \"name\": \"https://github.com/Kludex/starlette/commit/69ed26a85956ef4bd0161807eb27abf49be7cd3c\", \"tags\": [\"x_refsource_MISC\"]}, {\"url\": \"https://github.com/Kludex/starlette/releases/tag/0.49.1\", \"name\": \"https://github.com/Kludex/starlette/releases/tag/0.49.1\", \"tags\": [\"x_refsource_MISC\"]}], \"descriptions\": [{\"lang\": \"en\", \"value\": \"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\u0027s FileResponse Range parsing/merging logic. This enables CPU exhaustion per request, causing denial\\u2011of\\u2011service for endpoints serving files (e.g., StaticFiles or any use of FileResponse). This vulnerability is fixed in 0.49.1.\"}], \"problemTypes\": [{\"descriptions\": [{\"lang\": \"en\", \"type\": \"CWE\", \"cweId\": \"CWE-407\", \"description\": \"CWE-407: Inefficient Algorithmic Complexity\"}]}], \"providerMetadata\": {\"orgId\": \"a0819718-46f1-4df5-94e2-005712e83aaa\", \"shortName\": \"GitHub_M\", \"dateUpdated\": \"2025-11-04T17:41:42.316Z\"}}}",
      "cveMetadata": "{\"cveId\": \"CVE-2025-62727\", \"state\": \"PUBLISHED\", \"dateUpdated\": \"2025-11-04T17:41:42.316Z\", \"dateReserved\": \"2025-10-20T19:41:22.742Z\", \"assignerOrgId\": \"a0819718-46f1-4df5-94e2-005712e83aaa\", \"datePublished\": \"2025-10-28T20:14:53.655Z\", \"assignerShortName\": \"GitHub_M\"}",
      "dataType": "CVE_RECORD",
      "dataVersion": "5.2"
    }
  }
}



Log in or create an account to share your comment.




Tags
Taxonomy of the tags.





Forecast uses a logistic model when the trend is rising, or an exponential decay model when the trend is falling. Fitted via linearized least squares.

Sightings

Author Source Type Date Other

Nomenclature

  • Seen: The vulnerability was mentioned, discussed, or observed by the user.
  • Confirmed: The vulnerability has been validated from an analyst's perspective.
  • Published Proof of Concept: A public proof of concept is available for this vulnerability.
  • Exploited: The vulnerability was observed as exploited by the user who reported the sighting.
  • Patched: The vulnerability was observed as successfully patched by the user who reported the sighting.
  • Not exploited: The vulnerability was not observed as exploited by the user who reported the sighting.
  • Not confirmed: The user expressed doubt about the validity of the vulnerability.
  • Not patched: The vulnerability was not observed as successfully patched by the user who reported the sighting.


Detection rules are retrieved from Rulezet.