Unbounded chunk-size hex digits in cowlib cause quadratic CPU and memory DoS_CVE-2026-7790

{
    "lastseen": "",
    "description": "Uncontrolled Resource Consumption vulnerability in ninenines cowlib (cow_http_te module) allows Excessive Allocation.\n\nThe chunked transfer-encoding parser in cow_http_te accepts an unbounded number of hex digits in the chunk-size field. Each digit causes a bignum multiplication (Len * 16 + digit), so parsing N hex digits requires O(N\u00b2) CPU work and O(N) memory. Additionally, when input is drip-fed, the parser discards the accumulated length on each partial read and restarts from zero on resumption, raising the cost to O(N\u00b3). An unauthenticated remote attacker can exploit this by sending an HTTP/1.1 request with Transfer-Encoding: chunked and a very long chunk-size hex string to cause denial of service through CPU exhaustion and memory amplification.\n\nThis vulnerability is associated with program file src/cow_http_te.erl and program routines cow_http_te:stream_chunked/2, cow_http_te:chunked_len/4.\n\nThis issue affects cowlib: from 0.6.0 before 2.16.1.",
    "published": "2026-05-11T18:06:41.490Z",
    "modified": "2026-05-11T18:56:31.426Z",
    "type": "cve",
    "title": "Unbounded chunk-size hex digits in cowlib cause quadratic CPU and memory DoS",
    "source": "EEF",
    "references": "https://cna.erlef.org/cves/CVE-2026-7790.html\nhttps://osv.dev/vulnerability/EEF-CVE-2026-7790\nhttps://github.com/ninenines/cowlib/commit/a4b8039ce8c93ab00867ef6b7e888822c09f4369",
    "id": "CVE-2026-7790",
    "bulletinFamily": "",
    "cwe": [
        "CWE-400"
    ],
    "cvelist": null,
    "sourceData": "ninenines cowlib 0.6.0\nninenines cowlib 8c0e428b012c59f553a264f285ed89d36f791e3e",
    "sourceHref": "",
    "cvss": {
        "score": 8.7,
        "severity": "HIGH",
        "vector": "CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N",
        "version": "4.0"
    },
    "cvss2": [],
    "cvss3": {
        "version": "",
        "vectorString": "",
        "baseScore": 0,
        "baseSeverity": "",
        "attackVector": "",
        "attackComplexity": "",
        "privilegesRequired": "",
        "userInteraction": "",
        "scope": "",
        "confidentialityImpact": "",
        "integrityImpact": "",
        "availabilityImpact": "",
        "cvssV3": {
            "version": "",
            "vectorString": "",
            "baseScore": 0,
            "baseSeverity": "",
            "attackVector": "",
            "attackComplexity": "",
            "privilegesRequired": "",
            "userInteraction": "",
            "scope": "",
            "confidentialityImpact": "",
            "integrityImpact": "",
            "availabilityImpact": ""
        }
    },
    "href": "",
    "category_name": "CVE",
    "post_link": "",
    "product": "cowlib",
    "version": "0.6.0",
    "vendor": "ninenines",
    "ai_description": "Uncontrolled Resource Consumption vulnerability in cowlib allows Excessive Allocation through an unbounded number of hex digits in the chunk-size field, leading to denial of service through CPU exhaustion and memory amplification.",
    "ai_severity": "High",
    "ai_vendor": "ninenines",
    "ai_product": "cowlib",
    "ai_version": "0.6.0-2.16.0",
    "ai_score": 8.7
}