{
    "data_type": "CVE",
    "data_format": "MITRE",
    "data_version": "4.0",
    "CVE_data_meta": {
        "ID": "CVE-2021-38507",
        "ASSIGNER": "security@mozilla.org",
        "STATE": "PUBLIC"
    },
    "affects": {
        "vendor": {
            "vendor_data": [
                {
                    "vendor_name": "Mozilla",
                    "product": {
                        "product_data": [
                            {
                                "product_name": "Firefox",
                                "version": {
                                    "version_data": [
                                        {
                                            "version_value": "94",
                                            "version_affected": "<"
                                        }
                                    ]
                                }
                            },
                            {
                                "product_name": "Thunderbird",
                                "version": {
                                    "version_data": [
                                        {
                                            "version_value": "91.3",
                                            "version_affected": "<"
                                        }
                                    ]
                                }
                            },
                            {
                                "product_name": "Firefox ESR",
                                "version": {
                                    "version_data": [
                                        {
                                            "version_value": "91.3",
                                            "version_affected": "<"
                                        }
                                    ]
                                }
                            }
                        ]
                    }
                }
            ]
        }
    },
    "problemtype": {
        "problemtype_data": [
            {
                "description": [
                    {
                        "lang": "eng",
                        "value": "Opportunistic Encryption in HTTP2 could be used to bypass the Same-Origin-Policy on services hosted on other ports"
                    }
                ]
            }
        ]
    },
    "references": {
        "reference_data": [
            {
                "url": "https://www.mozilla.org/security/advisories/mfsa2021-49/",
                "refsource": "MISC",
                "name": "https://www.mozilla.org/security/advisories/mfsa2021-49/"
            },
            {
                "url": "https://www.mozilla.org/security/advisories/mfsa2021-50/",
                "refsource": "MISC",
                "name": "https://www.mozilla.org/security/advisories/mfsa2021-50/"
            },
            {
                "url": "https://www.mozilla.org/security/advisories/mfsa2021-48/",
                "refsource": "MISC",
                "name": "https://www.mozilla.org/security/advisories/mfsa2021-48/"
            },
            {
                "url": "https://bugzilla.mozilla.org/show_bug.cgi?id=1730935",
                "refsource": "MISC",
                "name": "https://bugzilla.mozilla.org/show_bug.cgi?id=1730935"
            },
            {
                "refsource": "DEBIAN",
                "name": "DSA-5026",
                "url": "https://www.debian.org/security/2021/dsa-5026"
            },
            {
                "refsource": "MLIST",
                "name": "[debian-lts-announce] 20211229 [SECURITY] [DLA 2863-1] firefox-esr security update",
                "url": "https://lists.debian.org/debian-lts-announce/2021/12/msg00030.html"
            },
            {
                "refsource": "DEBIAN",
                "name": "DSA-5034",
                "url": "https://www.debian.org/security/2022/dsa-5034"
            },
            {
                "refsource": "MLIST",
                "name": "[debian-lts-announce] 20220104 [SECURITY] [DLA 2874-1] thunderbird security update",
                "url": "https://lists.debian.org/debian-lts-announce/2022/01/msg00001.html"
            },
            {
                "refsource": "GENTOO",
                "name": "GLSA-202202-03",
                "url": "https://security.gentoo.org/glsa/202202-03"
            }
        ]
    },
    "description": {
        "description_data": [
            {
                "lang": "eng",
                "value": "The Opportunistic Encryption feature of HTTP2 (RFC 8164) allows a connection to be transparently upgraded to TLS while retaining the visual properties of an HTTP connection, including being same-origin with unencrypted connections on port 80. However, if a second encrypted port on the same IP address (e.g. port 8443) did not opt-in to opportunistic encryption; a network attacker could forward a connection from the browser to port 443 to port 8443, causing the browser to treat the content of port 8443 as same-origin with HTTP. This was resolved by disabling the Opportunistic Encryption feature, which had low usage. This vulnerability affects Firefox < 94, Thunderbird < 91.3, and Firefox ESR < 91.3."
            }
        ]
    }
}