FreeSWITCH: Pre-authentication heap buffer overflow in libesl `Content-Length` parsing_CVE-2026-49840

{
    "lastseen": "",
    "description": "FreeSWITCH is a Software Defined Telecom Stack enabling the digital transformation from proprietary telecom switches to a software implementation that runs on any commodity hardware. Prior to version 1.11.1, esl_recv_event() parses Content-Length with atol() and passes the result straight to malloc(len + 1) with no sign or magnitude check. A malicious or man-in-the-middle ESL peer can send a frame with a negative Content-Length to corrupt the heap of, or crash, any process linked against libesl, before the client has authenticated to that peer. This issue has been patched in version 1.11.1.",
    "published": "2026-06-09T16:00:56.687Z",
    "modified": "2026-06-09T16:00:56.687Z",
    "type": "cve",
    "title": "FreeSWITCH: Pre-authentication heap buffer overflow in libesl `Content-Length` parsing",
    "source": "GitHub_M",
    "references": "https://github.com/signalwire/freeswitch/security/advisories/GHSA-g597-9fgg-ghg9\nhttps://github.com/signalwire/freeswitch/releases/tag/v1.11.1",
    "id": "CVE-2026-49840",
    "bulletinFamily": "",
    "cwe": [
        "CWE-20",
        "CWE-122",
        "CWE-195",
        "CWE-787"
    ],
    "cvelist": null,
    "sourceData": "signalwire freeswitch < 1.11.1",
    "sourceHref": "",
    "cvss": {
        "score": 9.1,
        "severity": "CRITICAL",
        "vector": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:H",
        "version": "3.1"
    },
    "cvss2": [],
    "cvss3": {
        "version": "",
        "vectorString": "",
        "baseScore": 0,
        "baseSeverity": "",
        "attackVector": "",
        "attackComplexity": "",
        "privilegesRequired": "",
        "userInteraction": "",
        "scope": "",
        "confidentialityImpact": "",
        "integrityImpact": "",
        "availabilityImpact": "",
        "cvssV3": {
            "version": "",
            "vectorString": "",
            "baseScore": 0,
            "baseSeverity": "",
            "attackVector": "",
            "attackComplexity": "",
            "privilegesRequired": "",
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            "confidentialityImpact": "",
            "integrityImpact": "",
            "availabilityImpact": ""
        }
    },
    "href": "",
    "category_name": "CVE",
    "post_link": "",
    "product": "freeswitch",
    "version": "< 1.11.1",
    "vendor": "signalwire",
    "ai_description": "Pre-authentication heap buffer overflow in libesl `Content-Length` parsing",
    "ai_severity": "Critical",
    "ai_vendor": "SignalWire",
    "ai_product": "FreeSWITCH",
    "ai_version": "< 1.11.1",
    "ai_score": 9.1
}