{
    "dataType": "CVE_RECORD",
    "dataVersion": "5.2",
    "cveMetadata": {
        "cveId": "CVE-2026-59980",
        "assignerOrgId": "a0819718-46f1-4df5-94e2-005712e83aaa",
        "state": "PUBLISHED",
        "assignerShortName": "GitHub_M",
        "dateReserved": "2026-07-07T19:41:00.004Z",
        "datePublished": "2026-09-23T22:07:35.095Z",
        "dateUpdated": "2026-09-23T22:07:35.095Z"
    },
    "containers": {
        "cna": {
            "title": "hpack: Unbounded variable integer decoding can cause run-away computation on malformed input",
            "problemTypes": [
                {
                    "descriptions": [
                        {
                            "cweId": "CWE-400",
                            "lang": "en",
                            "description": "CWE-400: Uncontrolled Resource Consumption",
                            "type": "CWE"
                        }
                    ]
                }
            ],
            "metrics": [
                {
                    "cvssV4_0": {
                        "attackVector": "NETWORK",
                        "attackComplexity": "LOW",
                        "attackRequirements": "PRESENT",
                        "privilegesRequired": "NONE",
                        "userInteraction": "NONE",
                        "vulnConfidentialityImpact": "NONE",
                        "vulnIntegrityImpact": "NONE",
                        "vulnAvailabilityImpact": "LOW",
                        "subConfidentialityImpact": "NONE",
                        "subIntegrityImpact": "NONE",
                        "subAvailabilityImpact": "NONE",
                        "baseScore": 6.3,
                        "baseSeverity": "MEDIUM",
                        "vectorString": "CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:N/VI:N/VA:L/SC:N/SI:N/SA:N",
                        "version": "4.0"
                    }
                }
            ],
            "references": [
                {
                    "name": "https://github.com/python-hyper/hpack/security/advisories/GHSA-8v8h-hg4w-mvq2",
                    "tags": [
                        "x_refsource_CONFIRM"
                    ],
                    "url": "https://github.com/python-hyper/hpack/security/advisories/GHSA-8v8h-hg4w-mvq2"
                },
                {
                    "name": "https://github.com/python-hyper/hpack/commit/8cfb02c547740e16dbfe7aba77bad84b297cec2c",
                    "tags": [
                        "x_refsource_MISC"
                    ],
                    "url": "https://github.com/python-hyper/hpack/commit/8cfb02c547740e16dbfe7aba77bad84b297cec2c"
                },
                {
                    "name": "https://cs.opensource.google/go/x/net/+/master:http2/hpack/hpack.go;l=468;drc=8e2b117aee74f6b86c207a808b0255de45c0a18a",
                    "tags": [
                        "x_refsource_MISC"
                    ],
                    "url": "https://cs.opensource.google/go/x/net/+/master:http2/hpack/hpack.go;l=468;drc=8e2b117aee74f6b86c207a808b0255de45c0a18a"
                },
                {
                    "name": "https://docs.rs/http2/0.5.19/src/http2/hpack/decoder.rs.html#403",
                    "tags": [
                        "x_refsource_MISC"
                    ],
                    "url": "https://docs.rs/http2/0.5.19/src/http2/hpack/decoder.rs.html#403"
                }
            ],
            "affected": [
                {
                    "vendor": "python-hyper",
                    "product": "hpack",
                    "versions": [
                        {
                            "version": "< 4.2.0",
                            "status": "affected"
                        }
                    ]
                }
            ],
            "providerMetadata": {
                "orgId": "a0819718-46f1-4df5-94e2-005712e83aaa",
                "shortName": "GitHub_M",
                "dateUpdated": "2026-09-23T22:07:35.095Z"
            },
            "descriptions": [
                {
                    "lang": "en",
                    "value": "hpack is an HTTP/2 Header Encoding for Python. Prior to version 4.2.0, unbounded variable integer decoding can cause run-away computation on malformed input leading to O(n^2) runtime, effectively blocking further processing with large enough unsanitized input. A fix is available in python-hyper/hpack v4.2.0 to restricted variable integer decoding to uint32 to prevent run-away computation. As a workaround, sanitize input to hpack decoder for long sequences of `0xFF` values to prevent malicious use."
                }
            ],
            "source": {
                "advisory": "GHSA-8v8h-hg4w-mvq2",
                "discovery": "UNKNOWN"
            }
        }
    }
}