Vulnerability-Lookup

CVE-2026-59638 (GCVE-0-2026-59638)

Vulnerability from cvelistv5 – Published: 2026-08-03 00:57 – Updated: 2026-08-03 05:06

Title

JSSE hostname verifier CN-fallback enabled by default despite documented opt-in

Summary

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).

Severity

9.3 (Critical)


                        
                          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

CWE

CWE-297 - Improper Validation of Certificate with Host Mismatch

Assigner

bcorg

References

3 references

URL	Tags
https://github.com/bcgit/bc-java/wiki/CVE%E2%80%9…	vendor-advisory
https://github.com/bcgit/bc-java/commit/799bd1532…	patch
https://github.com/bcgit/bc-java/commit/5ac55351c…	patch

Impacted products

3 products

Vendor	Product	Version
Legion of the Bouncy Castle Inc.	BC-JAVA	Affected: 1.61 , < 1.85 (maven)
Legion of the Bouncy Castle Inc.	BC-LTS-JAVA	Affected: 2.73.0 , < 2.73.12 (maven)
Legion of the Bouncy Castle Inc.	BC-FJA	Affected: 1.0.7 , < 1.0.24 (maven) Affected: 2.0.0 , < 2.0.24 (maven) Affected: 2.1.0 , < 2.1.24 (maven)

Credits

Alex Gaynor in collaboration with Claude and Anthropic Research

Show details on NVD website

JSON

To clipboard

{
  "containers": {
    "cna": {
      "affected": [
        {
          "collectionURL": "https://www.bouncycastle.org/download/bouncy-castle-java/",
          "defaultStatus": "unaffected",
          "modules": [
            "tls"
          ],
          "packageName": "bctls",
          "packageURL": "pkg:maven/org.bouncycastle/bctls-jdk18on",
          "platforms": [
            "all"
          ],
          "product": "BC-JAVA",
          "programFiles": [
            "HostnameUtil"
          ],
          "repo": "https://github.com/bcgit/bc-java",
          "vendor": "Legion of the Bouncy Castle Inc.",
          "versions": [
            {
              "lessThan": "1.85",
              "status": "affected",
              "version": "1.61",
              "versionType": "maven"
            }
          ]
        },
        {
          "collectionURL": "https://www.bouncycastle.org/download/bouncy-castle-java-lts/",
          "defaultStatus": "unaffected",
          "modules": [
            "tls"
          ],
          "packageName": "bctls-lts8on",
          "packageURL": "pkg:maven/org.bouncycastle/bctls-lts8on",
          "platforms": [
            "all"
          ],
          "product": "BC-LTS-JAVA",
          "programFiles": [
            "HostnameUtil"
          ],
          "repo": "https://github.com/bcgit/bc-lts-java",
          "vendor": "Legion of the Bouncy Castle Inc.",
          "versions": [
            {
              "lessThan": "2.73.12",
              "status": "affected",
              "version": "2.73.0",
              "versionType": "maven"
            }
          ]
        },
        {
          "collectionURL": "https://www.bouncycastle.org/download/bouncy-castle-java-fips/",
          "defaultStatus": "unaffected",
          "packageName": "bctls-fips",
          "packageURL": "pkg:maven/org.bouncycastle/bctls-fips",
          "platforms": [
            "all"
          ],
          "product": "BC-FJA",
          "vendor": "Legion of the Bouncy Castle Inc.",
          "versions": [
            {
              "lessThan": "1.0.24",
              "status": "affected",
              "version": "1.0.7",
              "versionType": "maven"
            },
            {
              "lessThan": "2.0.24",
              "status": "affected",
              "version": "2.0.0",
              "versionType": "maven"
            },
            {
              "lessThan": "2.1.24",
              "status": "affected",
              "version": "2.1.0",
              "versionType": "maven"
            }
          ]
        }
      ],
      "credits": [
        {
          "lang": "en",
          "type": "reporter",
          "value": "Alex Gaynor in collaboration with Claude and Anthropic Research"
        }
      ],
      "descriptions": [
        {
          "lang": "en",
          "supportingMedia": [
            {
              "base64": false,
              "type": "text/html",
              "value": "\u003cp\u003eIn 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).\u003c/p\u003e"
            }
          ],
          "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)."
        }
      ],
      "metrics": [
        {
          "cvssV4_0": {
            "Automatable": "NOT_DEFINED",
            "Recovery": "NOT_DEFINED",
            "Safety": "NOT_DEFINED",
            "attackComplexity": "LOW",
            "attackRequirements": "NONE",
            "attackVector": "NETWORK",
            "baseScore": 9.3,
            "baseSeverity": "CRITICAL",
            "exploitMaturity": "NOT_DEFINED",
            "privilegesRequired": "NONE",
            "providerUrgency": "AMBER",
            "subAvailabilityImpact": "NONE",
            "subConfidentialityImpact": "NONE",
            "subIntegrityImpact": "NONE",
            "userInteraction": "NONE",
            "valueDensity": "NOT_DEFINED",
            "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",
            "version": "4.0",
            "vulnAvailabilityImpact": "NONE",
            "vulnConfidentialityImpact": "HIGH",
            "vulnIntegrityImpact": "HIGH",
            "vulnerabilityResponseEffort": "NOT_DEFINED"
          },
          "format": "CVSS",
          "scenarios": [
            {
              "lang": "en",
              "value": "GENERAL"
            }
          ]
        }
      ],
      "problemTypes": [
        {
          "descriptions": [
            {
              "cweId": "CWE-297",
              "description": "CWE-297 Improper Validation of Certificate with Host Mismatch",
              "lang": "en",
              "type": "CWE"
            }
          ]
        }
      ],
      "providerMetadata": {
        "dateUpdated": "2026-08-03T05:06:18.285Z",
        "orgId": "91579145-5d7b-4cc5-b925-a0262ff19630",
        "shortName": "bcorg"
      },
      "references": [
        {
          "tags": [
            "vendor-advisory"
          ],
          "url": "https://github.com/bcgit/bc-java/wiki/CVE%E2%80%902026%E2%80%9059638"
        },
        {
          "tags": [
            "patch"
          ],
          "url": "https://github.com/bcgit/bc-java/commit/799bd15320a6310a447863638aa3df64acef829b"
        },
        {
          "tags": [
            "patch"
          ],
          "url": "https://github.com/bcgit/bc-java/commit/5ac55351cd1a8a7184d41c96a7ee87df0770240a"
        }
      ],
      "source": {
        "discovery": "UNKNOWN"
      },
      "title": "JSSE hostname verifier CN-fallback enabled by default despite documented opt-in",
      "x_generator": {
        "engine": "bc release-notes template"
      }
    }
  },
  "cveMetadata": {
    "assignerOrgId": "91579145-5d7b-4cc5-b925-a0262ff19630",
    "assignerShortName": "bcorg",
    "cveId": "CVE-2026-59638",
    "datePublished": "2026-08-03T00:57:31.904Z",
    "dateReserved": "2026-07-06T06:58:29.263Z",
    "dateUpdated": "2026-08-03T05:06:18.285Z",
    "state": "PUBLISHED"
  },
  "dataType": "CVE_RECORD",
  "dataVersion": "5.2",
  "vulnerability-lookup:meta": {
    "nvd": "{\"cve\":{\"id\":\"CVE-2026-59638\",\"sourceIdentifier\":\"91579145-5d7b-4cc5-b925-a0262ff19630\",\"published\":\"2026-08-03T01:16:43.543\",\"lastModified\":\"2026-08-03T06:16:39.260\",\"vulnStatus\":\"Received\",\"cveTags\":[],\"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).\"}],\"affected\":[{\"source\":\"91579145-5d7b-4cc5-b925-a0262ff19630\",\"affectedData\":[{\"vendor\":\"Legion of the Bouncy Castle Inc.\",\"product\":\"BC-JAVA\",\"defaultStatus\":\"unaffected\",\"collectionURL\":\"https://www.bouncycastle.org/download/bouncy-castle-java/\",\"packageName\":\"bctls\",\"modules\":[\"tls\"],\"platforms\":[\"all\"],\"programFiles\":[\"HostnameUtil\"],\"repo\":\"https://github.com/bcgit/bc-java\",\"packageURL\":\"pkg:maven/org.bouncycastle/bctls-jdk18on\",\"versions\":[{\"version\":\"1.61\",\"lessThan\":\"1.85\",\"versionType\":\"maven\",\"status\":\"affected\"}]},{\"vendor\":\"Legion of the Bouncy Castle Inc.\",\"product\":\"BC-LTS-JAVA\",\"defaultStatus\":\"unaffected\",\"collectionURL\":\"https://www.bouncycastle.org/download/bouncy-castle-java-lts/\",\"packageName\":\"bctls-lts8on\",\"modules\":[\"tls\"],\"platforms\":[\"all\"],\"programFiles\":[\"HostnameUtil\"],\"repo\":\"https://github.com/bcgit/bc-lts-java\",\"packageURL\":\"pkg:maven/org.bouncycastle/bctls-lts8on\",\"versions\":[{\"version\":\"2.73.0\",\"lessThan\":\"2.73.12\",\"versionType\":\"maven\",\"status\":\"affected\"}]},{\"vendor\":\"Legion of the Bouncy Castle Inc.\",\"product\":\"BC-FJA\",\"defaultStatus\":\"unaffected\",\"collectionURL\":\"https://www.bouncycastle.org/download/bouncy-castle-java-fips/\",\"packageName\":\"bctls-fips\",\"platforms\":[\"all\"],\"packageURL\":\"pkg:maven/org.bouncycastle/bctls-fips\",\"versions\":[{\"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\",\"status\":\"affected\"}]}]}],\"metrics\":{\"cvssMetricV40\":[{\"source\":\"91579145-5d7b-4cc5-b925-a0262ff19630\",\"type\":\"Secondary\",\"cvssData\":{\"version\":\"4.0\",\"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/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:Amber\",\"baseScore\":9.3,\"baseSeverity\":\"CRITICAL\",\"attackVector\":\"NETWORK\",\"attackComplexity\":\"LOW\",\"attackRequirements\":\"NONE\",\"privilegesRequired\":\"NONE\",\"userInteraction\":\"NONE\",\"vulnConfidentialityImpact\":\"HIGH\",\"vulnIntegrityImpact\":\"HIGH\",\"vulnAvailabilityImpact\":\"NONE\",\"subConfidentialityImpact\":\"NONE\",\"subIntegrityImpact\":\"NONE\",\"subAvailabilityImpact\":\"NONE\",\"exploitMaturity\":\"NOT_DEFINED\",\"confidentialityRequirement\":\"NOT_DEFINED\",\"integrityRequirement\":\"NOT_DEFINED\",\"availabilityRequirement\":\"NOT_DEFINED\",\"modifiedAttackVector\":\"NOT_DEFINED\",\"modifiedAttackComplexity\":\"NOT_DEFINED\",\"modifiedAttackRequirements\":\"NOT_DEFINED\",\"modifiedPrivilegesRequired\":\"NOT_DEFINED\",\"modifiedUserInteraction\":\"NOT_DEFINED\",\"modifiedVulnConfidentialityImpact\":\"NOT_DEFINED\",\"modifiedVulnIntegrityImpact\":\"NOT_DEFINED\",\"modifiedVulnAvailabilityImpact\":\"NOT_DEFINED\",\"modifiedSubConfidentialityImpact\":\"NOT_DEFINED\",\"modifiedSubIntegrityImpact\":\"NOT_DEFINED\",\"modifiedSubAvailabilityImpact\":\"NOT_DEFINED\",\"Safety\":\"NOT_DEFINED\",\"Automatable\":\"NOT_DEFINED\",\"Recovery\":\"NOT_DEFINED\",\"valueDensity\":\"NOT_DEFINED\",\"vulnerabilityResponseEffort\":\"NOT_DEFINED\",\"providerUrgency\":\"AMBER\"}}]},\"weaknesses\":[{\"source\":\"91579145-5d7b-4cc5-b925-a0262ff19630\",\"type\":\"Secondary\",\"description\":[{\"lang\":\"en\",\"value\":\"CWE-297\"}]}],\"references\":[{\"url\":\"https://github.com/bcgit/bc-java/commit/5ac55351cd1a8a7184d41c96a7ee87df0770240a\",\"source\":\"91579145-5d7b-4cc5-b925-a0262ff19630\"},{\"url\":\"https://github.com/bcgit/bc-java/commit/799bd15320a6310a447863638aa3df64acef829b\",\"source\":\"91579145-5d7b-4cc5-b925-a0262ff19630\"},{\"url\":\"https://github.com/bcgit/bc-java/wiki/CVE%E2%80%902026%E2%80%9059638\",\"source\":\"91579145-5d7b-4cc5-b925-a0262ff19630\"}]}}"
  }
}

GHSA-8RXJ-3P7P-RQ39

Vulnerability from github – Published: 2026-08-03 03:31 – Updated: 2026-08-03 06:31

Details

Severity

9.3 (Critical)


                  
                    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

Show details on source website

JSON

To clipboard

{
  "affected": [],
  "aliases": [
    "CVE-2026-59638"
  ],
  "database_specific": {
    "cwe_ids": [
      "CWE-297"
    ],
    "github_reviewed": false,
    "github_reviewed_at": null,
    "nvd_published_at": "2026-08-03T01:16:43Z",
    "severity": "CRITICAL"
  },
  "details": "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).",
  "id": "GHSA-8rxj-3p7p-rq39",
  "modified": "2026-08-03T06:31:42Z",
  "published": "2026-08-03T03:31:54Z",
  "references": [
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-59638"
    },
    {
      "type": "WEB",
      "url": "https://github.com/bcgit/bc-java/commit/5ac55351cd1a8a7184d41c96a7ee87df0770240a"
    },
    {
      "type": "WEB",
      "url": "https://github.com/bcgit/bc-java/commit/799bd15320a6310a447863638aa3df64acef829b"
    },
    {
      "type": "WEB",
      "url": "https://github.com/bcgit/bc-java/wiki/CVE%E2%80%902026%E2%80%9059638"
    },
    {
      "type": "WEB",
      "url": "https://github.com/bcgit/bc-java/wiki/CVE-2026-59638"
    }
  ],
  "schema_version": "1.4.0",
  "severity": [
    {
      "score": "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/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:Amber",
      "type": "CVSS_V4"
    }
  ]
}

Sightings

Author	Source	Type	Date	Other

Nomenclature

Seen: The vulnerability was mentioned, discussed, or observed by the user.
Confirmed: The vulnerability has been validated from an analyst's perspective.
Published Proof of Concept: A public proof of concept is available for this vulnerability.
Exploited: The vulnerability was observed as exploited by the user who reported the sighting.
Patched: The vulnerability was observed as successfully patched by the user who reported the sighting.
Not exploited: The vulnerability was not observed as exploited by the user who reported the sighting.
Not confirmed: The user expressed doubt about the validity of the vulnerability.
Not patched: The vulnerability was not observed as successfully patched by the user who reported the sighting.

Detection rules are retrieved from Rulezet.

The MITRE ATT&CK techniques below are AI-generated suggestions, inferred from the description of the vulnerability by the CIRCL/vulnerability-attack-technique-classification-roberta-base model, served locally by ML-Gateway. They have not been verified by an analyst and are provided for guidance only.

Action not permitted

CVE-2026-59638 (GCVE-0-2026-59638)

GHSA-8RXJ-3P7P-RQ39

Tags

Sightings

Nomenclature