{
    "dataType": "CVE_RECORD",
    "dataVersion": "5.2",
    "cveMetadata": {
        "cveId": "CVE-2026-59638",
        "assignerOrgId": "91579145-5d7b-4cc5-b925-a0262ff19630",
        "state": "PUBLISHED",
        "assignerShortName": "bcorg",
        "dateReserved": "2026-07-06T06:58:29.263Z",
        "datePublished": "2026-08-03T00:57:31.904Z",
        "dateUpdated": "2026-08-03T13:23:06.454Z"
    },
    "containers": {
        "cna": {
            "providerMetadata": {
                "orgId": "91579145-5d7b-4cc5-b925-a0262ff19630",
                "shortName": "bcorg",
                "dateUpdated": "2026-08-03T05:06:18.285Z"
            },
            "title": "JSSE hostname verifier CN-fallback enabled by default despite documented opt-in",
            "problemTypes": [
                {
                    "descriptions": [
                        {
                            "lang": "en",
                            "cweId": "CWE-297",
                            "description": "CWE-297 Improper Validation of Certificate with Host Mismatch",
                            "type": "CWE"
                        }
                    ]
                }
            ],
            "affected": [
                {
                    "vendor": "Legion of the Bouncy Castle Inc.",
                    "product": "BC-JAVA",
                    "platforms": [
                        "all"
                    ],
                    "collectionURL": "https://www.bouncycastle.org/download/bouncy-castle-java/",
                    "packageName": "bctls",
                    "repo": "https://github.com/bcgit/bc-java",
                    "packageURL": "pkg:maven/org.bouncycastle/bctls-jdk18on",
                    "modules": [
                        "tls"
                    ],
                    "programFiles": [
                        "HostnameUtil"
                    ],
                    "versions": [
                        {
                            "status": "affected",
                            "version": "1.61",
                            "lessThan": "1.85",
                            "versionType": "maven"
                        }
                    ],
                    "defaultStatus": "unaffected"
                },
                {
                    "vendor": "Legion of the Bouncy Castle Inc.",
                    "product": "BC-LTS-JAVA",
                    "platforms": [
                        "all"
                    ],
                    "collectionURL": "https://www.bouncycastle.org/download/bouncy-castle-java-lts/",
                    "packageName": "bctls-lts8on",
                    "repo": "https://github.com/bcgit/bc-lts-java",
                    "packageURL": "pkg:maven/org.bouncycastle/bctls-lts8on",
                    "modules": [
                        "tls"
                    ],
                    "programFiles": [
                        "HostnameUtil"
                    ],
                    "versions": [
                        {
                            "status": "affected",
                            "version": "2.73.0",
                            "lessThan": "2.73.12",
                            "versionType": "maven"
                        }
                    ],
                    "defaultStatus": "unaffected"
                },
                {
                    "vendor": "Legion of the Bouncy Castle Inc.",
                    "product": "BC-FJA",
                    "platforms": [
                        "all"
                    ],
                    "collectionURL": "https://www.bouncycastle.org/download/bouncy-castle-java-fips/",
                    "packageName": "bctls-fips",
                    "packageURL": "pkg:maven/org.bouncycastle/bctls-fips",
                    "versions": [
                        {
                            "status": "affected",
                            "version": "1.0.7",
                            "lessThan": "1.0.24",
                            "versionType": "maven"
                        },
                        {
                            "status": "affected",
                            "version": "2.0.0",
                            "lessThan": "2.0.24",
                            "versionType": "maven"
                        },
                        {
                            "status": "affected",
                            "version": "2.1.0",
                            "lessThan": "2.1.24",
                            "versionType": "maven"
                        }
                    ],
                    "defaultStatus": "unaffected"
                }
            ],
            "descriptions": [
                {
                    "lang": "en",
                    "value": "In Bouncy Castle for Java before 1.85, JSSE hostname verifier CN-fallback enabled by default despite documented opt-in. This issue also affects Bouncy Castle for Java LTS before 2.73.12, and Bouncy Castle for Java FIPS (BC-FJA) before bctls-fips 1.0.24 (1.0.X series), 2.0.24 (2.0.X series) and 2.1.24 (2.1.X series).",
                    "supportingMedia": [
                        {
                            "type": "text/html",
                            "base64": false,
                            "value": "<p>In Bouncy Castle for Java before 1.85, JSSE hostname verifier CN-fallback enabled by default despite documented opt-in. This issue also affects Bouncy Castle for Java LTS before 2.73.12, and Bouncy Castle for Java FIPS (BC-FJA) before bctls-fips 1.0.24 (1.0.X series), 2.0.24 (2.0.X series) and 2.1.24 (2.1.X series).</p>"
                        }
                    ]
                }
            ],
            "references": [
                {
                    "url": "https://github.com/bcgit/bc-java/wiki/CVE%E2%80%902026%E2%80%9059638",
                    "tags": [
                        "vendor-advisory"
                    ]
                },
                {
                    "url": "https://github.com/bcgit/bc-java/commit/799bd15320a6310a447863638aa3df64acef829b",
                    "tags": [
                        "patch"
                    ]
                },
                {
                    "url": "https://github.com/bcgit/bc-java/commit/5ac55351cd1a8a7184d41c96a7ee87df0770240a",
                    "tags": [
                        "patch"
                    ]
                }
            ],
            "metrics": [
                {
                    "format": "CVSS",
                    "scenarios": [
                        {
                            "lang": "en",
                            "value": "GENERAL"
                        }
                    ],
                    "cvssV4_0": {
                        "attackVector": "NETWORK",
                        "attackComplexity": "LOW",
                        "attackRequirements": "NONE",
                        "privilegesRequired": "NONE",
                        "userInteraction": "NONE",
                        "vulnConfidentialityImpact": "HIGH",
                        "subConfidentialityImpact": "NONE",
                        "vulnIntegrityImpact": "HIGH",
                        "subIntegrityImpact": "NONE",
                        "vulnAvailabilityImpact": "NONE",
                        "subAvailabilityImpact": "NONE",
                        "exploitMaturity": "NOT_DEFINED",
                        "Safety": "NOT_DEFINED",
                        "Automatable": "NOT_DEFINED",
                        "Recovery": "NOT_DEFINED",
                        "valueDensity": "NOT_DEFINED",
                        "vulnerabilityResponseEffort": "NOT_DEFINED",
                        "providerUrgency": "AMBER",
                        "version": "4.0",
                        "baseSeverity": "CRITICAL",
                        "baseScore": 9.3,
                        "vectorString": "CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:H/VA:N/SC:N/SI:N/SA:N/U:Amber"
                    }
                }
            ],
            "credits": [
                {
                    "lang": "en",
                    "value": "Alex Gaynor in collaboration with Claude and Anthropic Research",
                    "type": "reporter"
                }
            ],
            "source": {
                "discovery": "UNKNOWN"
            },
            "x_generator": {
                "engine": "bc release-notes template"
            }
        },
        "adp": [
            {
                "metrics": [
                    {
                        "other": {
                            "type": "ssvc",
                            "content": {
                                "timestamp": "2026-08-03T13:22:54.412148Z",
                                "id": "CVE-2026-59638",
                                "options": [
                                    {
                                        "Exploitation": "none"
                                    },
                                    {
                                        "Automatable": "yes"
                                    },
                                    {
                                        "Technical Impact": "total"
                                    }
                                ],
                                "role": "CISA Coordinator",
                                "version": "2.0.3"
                            }
                        }
                    }
                ],
                "title": "CISA ADP Vulnrichment",
                "providerMetadata": {
                    "orgId": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
                    "shortName": "CISA-ADP",
                    "dateUpdated": "2026-08-03T13:23:06.454Z"
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