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.

Database specific

{
    "cna_assigner": "GitHub_M",
    "cwe_ids": [
        "CWE-407"
    ],
    "osv_generated_from": "https://github.com/CVEProject/cvelistV5/tree/main/cves/2025/62xxx/CVE-2025-62727.json"
}

References

Affected packages

Git / github.com/kludex/starlette

Affected ranges

Type

GIT

Repo

https://github.com/kludex/starlette

Events

Introduced

65bfd74307f593505aaa4c399f73e4d90cd8aa78

Fixed

7e4b7428f273dbdc875dcd036d20804bcfc7b2ee

Fixed

4ea6e22b489ec388d6004cfbca52dd5b147127c5

Fixed

69ed26a85956ef4bd0161807eb27abf49be7cd3c

Database specific

Show details

{
    "extracted_events": [
        {
            "range": [
                {
                    "introduced": "0.39.0"
                },
                {
                    "fixed": "0.49.1"
                }
            ],
            "source": "AFFECTED_FIELD",
            "strategy": "StringRangeExpression"
        },
        {
            "range": [
                {
                    "fixed": "4ea6e22b489ec388d6004cfbca52dd5b147127c5"
                }
            ],
            "source": "REFERENCES_COMMIT"
        },
        {
            "range": [
                {
                    "fixed": "69ed26a85956ef4bd0161807eb27abf49be7cd3c"
                }
            ],
            "source": "REFERENCES_COMMIT"
        },
        {
            "original_tag": "0.49.1",
            "range": [
                {
                    "fixed": "7e4b7428f273dbdc875dcd036d20804bcfc7b2ee"
                }
            ],
            "source": "REFERENCES_TAG"
        }
    ]
}

Affected versions

0.*

0.39.0

0.39.1

0.39.2

0.40.0

0.41.0

0.41.1

0.41.2

0.41.3

0.42.0

0.43.0

0.44.0

0.45.0

0.45.1

0.45.2

0.45.3

0.46.0

0.46.1

0.46.2

0.47.0

0.47.1

0.47.2

0.47.3

0.48.0

0.49.0

Database specific

source

"https://storage.googleapis.com/osv-test-cve-osv-conversion/osv-output/CVE-2025-62727.json"