gun HTTP/2 PUSH_PROMISE authority not validated against connection origin allows cross-origin cookie injection_CVE-2026-43972

{
    "lastseen": "",
    "description": "Origin Validation Error vulnerability in ninenines gun (gun_http2 module) allows cross-origin cookie injection via unvalidated HTTP/2 PUSH_PROMISE authority.\n\nIn gun_http2:push_promise_frame/7, the :authority pseudo-header from an incoming PUSH_PROMISE frame is stored verbatim into the promised stream record without checking that it matches the connection's origin. When gun_http2:headers_frame/9 later processes the response headers for the promised stream, it calls gun_cookies:set_cookie_header/7 with the unvalidated server-supplied authority before any status branching and before user code can act. This violates RFC 7540 \u00a710.6 / RFC 9113 \u00a78.4, which require receivers to treat as a protocol error any push for a resource the server is not authoritative for.\n\nA malicious or compromised HTTP/2 server can plant cookies scoped to arbitrary third-party domains into the client's shared cookie store. This enables session fixation attacks against those domains and, if the planted cookie overrides a legitimate session token, may result in account takeover. No user interaction beyond making a normal HTTP/2 request to the attacker-controlled server is required.\n\nThis issue affects gun: from 2.0.0 before 2.4.0.",
    "published": "2026-06-08T14:12:38.780Z",
    "modified": "2026-06-08T14:15:56.058Z",
    "type": "cve",
    "title": "gun HTTP/2 PUSH_PROMISE authority not validated against connection origin allows cross-origin cookie injection",
    "source": "EEF",
    "references": "https://cna.erlef.org/cves/CVE-2026-43972.html\nhttps://osv.dev/vulnerability/EEF-CVE-2026-43972\nhttps://github.com/ninenines/gun/commit/567863ff53802fed21c3b3f25812db7f7ae29676",
    "id": "CVE-2026-43972",
    "bulletinFamily": "",
    "cwe": [
        "CWE-346"
    ],
    "cvelist": null,
    "sourceData": "ninenines gun 2.0.0\nninenines gun 871989eef53663285c165fdfb83a5918ebe00d41",
    "sourceHref": "",
    "cvss": {
        "score": 6.3,
        "severity": "MEDIUM",
        "vector": "CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:N/VI:L/VA:N/SC:L/SI:L/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": "",
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            "confidentialityImpact": "",
            "integrityImpact": "",
            "availabilityImpact": ""
        }
    },
    "href": "",
    "category_name": "CVE",
    "post_link": "",
    "product": "gun",
    "version": "2.0.0",
    "vendor": "ninenines",
    "ai_description": "",
    "ai_severity": "",
    "ai_vendor": "",
    "ai_product": "",
    "ai_version": "",
    "ai_score": 0
}