Envoy: Embedded NUL in TLS DNS SAN Truncation in the Default TLS Certificate Validator. (Auth Bypass)_CVE-2026-47778

{
    "lastseen": "",
    "description": "Envoy is an open source edge and service proxy designed for cloud-native applications. Prior to 1.35.11, 1.36.7, 1.37.3, and 1.38.1, a structural flaw was identified in DefaultCertValidator::verifySubjectAltName where the extracted DNS SAN string is cast to a C-style string using .c_str() before being passed to the Utility::dnsNameMatch() algorithm. If the attacker serves a certificate with a dNSName SAN containing an embedded NUL byte, the helper Utility::generalNameAsString captures the complete string including the NUL. However, when .c_str() evaluates it, implicit conversion to absl::string_view inside dnsNameMatch relies on strlen(), prematurely truncating the evaluation context. Envoy evaluates trucated string against the exact required config_san match and returns true, thereby successfully validating the string with the Nul byte for an upstream routing. This vulnerability is fixed in 1.35.11, 1.36.7, 1.37.3, and 1.38.1.",
    "published": "2026-06-26T17:27:57.707Z",
    "modified": "2026-06-26T17:27:57.707Z",
    "type": "cve",
    "title": "Envoy: Embedded NUL in TLS DNS SAN Truncation in the Default TLS Certificate Validator. (Auth Bypass)",
    "source": "GitHub_M",
    "references": "https://github.com/envoyproxy/envoy/security/advisories/GHSA-f8x4-rw5x-f3r7",
    "id": "CVE-2026-47778",
    "bulletinFamily": "",
    "cwe": [
        "CWE-158"
    ],
    "cvelist": null,
    "sourceData": "envoyproxy envoy >= 1.38.0, < 1.38.1\nenvoyproxy envoy >= 1.37.0, < 1.37.3\nenvoyproxy envoy >= 1.36.0, < 1.36.7\nenvoyproxy envoy < 1.35.11",
    "sourceHref": "",
    "cvss": {
        "score": 4.4,
        "severity": "MEDIUM",
        "vector": "CVSS:3.1/AV:N/AC:H/PR:H/UI:N/S:U/C:H/I:N/A:N",
        "version": "3.1"
    },
    "cvss2": [],
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    },
    "href": "",
    "category_name": "CVE",
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    "product": "envoy",
    "version": ">= 1.38.0, < 1.38.1",
    "vendor": "envoyproxy",
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}