Improper certificate validation in the directoryName name-constraint check (PkixNameConstraintValidator.WithinDNSubtree) in Legion of the Bouncy Castle Inc. bc-csharp before 2.7.0 allows an attacker who controls, or can have certificates issued by, a name-constrained intermediate CA to get certificates accepted by PKIX path validation whose subject distinguished name, or a directoryName subjectAltName, lies outside the CA's permitted subtrees, via a name that places other RDNs ahead of a copy of the permitted RDN sequence, because the check looks for the constraint's first RDN anywhere in the name and compares the remaining RDNs from that position, instead of requiring the constraint to be an initial prefix of the name as RFC 5280 sections 4.2.1.10 and 7.1 require.

zetlyn/cve-nvd vulnerability cve CVE-2026-63577 known 2026-10-02

https://nvd.nist.gov/vuln/detail/CVE-2026-63577

Properties

productbc-csharp
receipt
Source
NVD
Its words
bc-csharp
Read by
field:cve.affected[].affectedData[].product
Said since
2026-10-02 12:00 UTC
Last answered
2026-10-04 18:16 UTC
Original
open at the source
What the source handed over
{
  "cve": {
    "affected": [
      {
        "affectedData": [
          {
            "collectionURL": "https://www.nuget.org/packages/BouncyCastle.Cryptography",
            "defaultStatus": "unaffected",
            "packageName": "BouncyCastle.Cryptography",
            "product": "bc-csharp",
            "programFiles": [
              "crypto/src/pkix/PkixNameConstraintValidator.cs"
            ],
            "repo": "https://github.com/bcgit/bc-csharp",
            "vendor": "Legion of the Bouncy Castle Inc.",
            "versions": [
              {
                "lessThan": "2.7.0",
                "status": "affected",
                "version": "0",
                "versionType": "semver"
              }
            ]
          }
        ],
        "source": "91579145-5d7b-4cc5-b925-a0262ff19630"
      }
    ],
    "cveTags": [],
    "descriptions": [
      {
        "lang": "en",
        "value": "Improper certificate validation in the directoryName name-constraint check (PkixNameConstraintValidator.WithinDNSubtree) in Legion of the Bouncy Castle Inc. bc-csharp before 2.7.0 allows an attacker who controls, or can have certificates issued by, a name-constrained intermediate CA to get certificates accepted by PKIX path validation whose subject distinguished name, or a directoryName subjectAltName, lies outside the CA's permitted subtrees, via a name that places other RDNs ahead of a copy of the permitted RDN sequence, because the check looks for the constraint's first RDN anywhere in the name and compares the remaining RDNs from that position, instead of requiring the constraint to be an initial prefix of the name as RFC 5280 sections 4.2.1.10 and 7.1 require."
      }
    ],
    "id": "CVE-2026-63577",
    "lastModified": "2026-10-02T14:44:52.247",
    "metrics": {
      "cvssMetricV40": [
        {
          "cvssData": {
            "Automatable": "NOT_DEFINED",
            "Recovery": "NOT_DEFINED",
            "Safety": "NOT_DEFINED",
            "attackComplexity": "LOW",
            "attackRequirements": "PRESENT",
            "attackVector": "NETWORK",
            "availabilityRequirement": "NOT_DEFINED",
            "baseScore": 8.2,
            "baseSeverity": "HIGH",
            "confidentialityRequirement": "NOT_DEFINED",
            "exploitMaturity": "NOT_DEFINED",
            "integrityRequirement": "NOT_DEFINED",
            "modifiedAttackComplexity": "NOT_DEFINED",
            "modifiedAttackRequirements": "NOT_DEFINED",
            "modifiedAttackVector": "NOT_DEFINED",
            "modifiedPrivilegesRequired": "NOT_DEFINED",
            "modifiedSubAvailabilityImpact": "NOT_DEFINED",
            "modifiedSubConfidentialityImpact": "NOT_DEFINED",
            "modifiedSubIntegrityImpact": "NOT_DEFINED",
            "modifiedUserInteraction": "NOT_DEFINED",
            "modifiedVulnAvailabilityImpact": "NOT_DEFINED",
            "modifiedVulnConfidentialityImpact": "NOT_DEFINED",
            "modifiedVulnIntegrityImpact": "NOT_DEFINED",
            "privilegesRequired": "NONE",
            "providerUrgency": "NOT_DEFINED",
            "subAvailabilityImpact": "NONE",
            "subConfidentialityImpact": "NONE",
            "subIntegrityImpact": "NONE",
            "userInteraction": "NONE",
            "valueDensity": "NOT_DEFINED",
            "vectorString": "CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:N/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:X",
            "version": "4.0",
            "vulnAvailabilityImpact": "NONE",
            "vulnConfidentialityImpact": "NONE",
            "vulnIntegrityImpact": "HIGH",
            "vulnerabilityResponseEffort": "NOT_DEFINED"
          },
          "source": "91579145-5d7b-4cc5-b925-a0262ff19630",
          "type": "Secondary"
        }
      ]
    },
    "published": "2026-10-02T08:17:02.937",
    "references": [
      {
        "source": "91579145-5d7b-4cc5-b925-a0262ff19630",
        "url": "https://github.com/bcgit/bc-csharp/commit/606e9153b97a265c70ca8293d21ec859344d7de8"
      },
      {
        "source": "91579145-5d7b-4cc5-b925-a0262ff19630",
        "url": "https://github.com/bcgit/bc-csharp/commit/75c3c576602886180ed92a63c89419e3bd63b392"
      },
      {
        "source": "91579145-5d7b-4cc5-b925-a0262ff19630",
        "url": "https://github.com/bcgit/bc-csharp/wiki/CVE-2026-63577"
      }
    ],
    "sourceIdentifier": "91579145-5d7b-4cc5-b925-a0262ff19630",
    "vulnStatus": "Undergoing Analysis",
    "weaknesses": [
      {
        "description": [
          {
            "lang": "en",
            "value": "CWE-295"
          }
        ],
        "source": "91579145-5d7b-4cc5-b925-a0262ff19630",
        "type": "Secondary"
      }
    ]
  }
}
statusUndergoing Analysis
receipt
Source
NVD
Its words
Undergoing Analysis
Read by
field:cve.vulnStatus
Said since
2026-10-03 00:06 UTC
Last answered
2026-10-04 18:16 UTC
Original
open at the source
2026-10-03 00:06 UTCUndergoing Analysis
2026-10-02 18:03 UTCAwaiting Analysis
2026-10-02 12:00 UTCReceived
What the source handed over
{
  "cve": {
    "affected": [
      {
        "affectedData": [
          {
            "collectionURL": "https://www.nuget.org/packages/BouncyCastle.Cryptography",
            "defaultStatus": "unaffected",
            "packageName": "BouncyCastle.Cryptography",
            "product": "bc-csharp",
            "programFiles": [
              "crypto/src/pkix/PkixNameConstraintValidator.cs"
            ],
            "repo": "https://github.com/bcgit/bc-csharp",
            "vendor": "Legion of the Bouncy Castle Inc.",
            "versions": [
              {
                "lessThan": "2.7.0",
                "status": "affected",
                "version": "0",
                "versionType": "semver"
              }
            ]
          }
        ],
        "source": "91579145-5d7b-4cc5-b925-a0262ff19630"
      }
    ],
    "cveTags": [],
    "descriptions": [
      {
        "lang": "en",
        "value": "Improper certificate validation in the directoryName name-constraint check (PkixNameConstraintValidator.WithinDNSubtree) in Legion of the Bouncy Castle Inc. bc-csharp before 2.7.0 allows an attacker who controls, or can have certificates issued by, a name-constrained intermediate CA to get certificates accepted by PKIX path validation whose subject distinguished name, or a directoryName subjectAltName, lies outside the CA's permitted subtrees, via a name that places other RDNs ahead of a copy of the permitted RDN sequence, because the check looks for the constraint's first RDN anywhere in the name and compares the remaining RDNs from that position, instead of requiring the constraint to be an initial prefix of the name as RFC 5280 sections 4.2.1.10 and 7.1 require."
      }
    ],
    "id": "CVE-2026-63577",
    "lastModified": "2026-10-02T14:44:52.247",
    "metrics": {
      "cvssMetricV40": [
        {
          "cvssData": {
            "Automatable": "NOT_DEFINED",
            "Recovery": "NOT_DEFINED",
            "Safety": "NOT_DEFINED",
            "attackComplexity": "LOW",
            "attackRequirements": "PRESENT",
            "attackVector": "NETWORK",
            "availabilityRequirement": "NOT_DEFINED",
            "baseScore": 8.2,
            "baseSeverity": "HIGH",
            "confidentialityRequirement": "NOT_DEFINED",
            "exploitMaturity": "NOT_DEFINED",
            "integrityRequirement": "NOT_DEFINED",
            "modifiedAttackComplexity": "NOT_DEFINED",
            "modifiedAttackRequirements": "NOT_DEFINED",
            "modifiedAttackVector": "NOT_DEFINED",
            "modifiedPrivilegesRequired": "NOT_DEFINED",
            "modifiedSubAvailabilityImpact": "NOT_DEFINED",
            "modifiedSubConfidentialityImpact": "NOT_DEFINED",
            "modifiedSubIntegrityImpact": "NOT_DEFINED",
            "modifiedUserInteraction": "NOT_DEFINED",
            "modifiedVulnAvailabilityImpact": "NOT_DEFINED",
            "modifiedVulnConfidentialityImpact": "NOT_DEFINED",
            "modifiedVulnIntegrityImpact": "NOT_DEFINED",
            "privilegesRequired": "NONE",
            "providerUrgency": "NOT_DEFINED",
            "subAvailabilityImpact": "NONE",
            "subConfidentialityImpact": "NONE",
            "subIntegrityImpact": "NONE",
            "userInteraction": "NONE",
            "valueDensity": "NOT_DEFINED",
            "vectorString": "CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:N/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:X",
            "version": "4.0",
            "vulnAvailabilityImpact": "NONE",
            "vulnConfidentialityImpact": "NONE",
            "vulnIntegrityImpact": "HIGH",
            "vulnerabilityResponseEffort": "NOT_DEFINED"
          },
          "source": "91579145-5d7b-4cc5-b925-a0262ff19630",
          "type": "Secondary"
        }
      ]
    },
    "published": "2026-10-02T08:17:02.937",
    "references": [
      {
        "source": "91579145-5d7b-4cc5-b925-a0262ff19630",
        "url": "https://github.com/bcgit/bc-csharp/commit/606e9153b97a265c70ca8293d21ec859344d7de8"
      },
      {
        "source": "91579145-5d7b-4cc5-b925-a0262ff19630",
        "url": "https://github.com/bcgit/bc-csharp/commit/75c3c576602886180ed92a63c89419e3bd63b392"
      },
      {
        "source": "91579145-5d7b-4cc5-b925-a0262ff19630",
        "url": "https://github.com/bcgit/bc-csharp/wiki/CVE-2026-63577"
      }
    ],
    "sourceIdentifier": "91579145-5d7b-4cc5-b925-a0262ff19630",
    "vulnStatus": "Undergoing Analysis",
    "weaknesses": [
      {
        "description": [
          {
            "lang": "en",
            "value": "CWE-295"
          }
        ],
        "source": "91579145-5d7b-4cc5-b925-a0262ff19630",
        "type": "Secondary"
      }
    ]
  }
}
vendorLegion of the Bouncy Castle Inc.
receipt
Source
NVD
Its words
Legion of the Bouncy Castle Inc.
Read by
field:cve.affected[].affectedData[].vendor
Said since
2026-10-02 12:00 UTC
Last answered
2026-10-04 18:16 UTC
Original
open at the source
What the source handed over
{
  "cve": {
    "affected": [
      {
        "affectedData": [
          {
            "collectionURL": "https://www.nuget.org/packages/BouncyCastle.Cryptography",
            "defaultStatus": "unaffected",
            "packageName": "BouncyCastle.Cryptography",
            "product": "bc-csharp",
            "programFiles": [
              "crypto/src/pkix/PkixNameConstraintValidator.cs"
            ],
            "repo": "https://github.com/bcgit/bc-csharp",
            "vendor": "Legion of the Bouncy Castle Inc.",
            "versions": [
              {
                "lessThan": "2.7.0",
                "status": "affected",
                "version": "0",
                "versionType": "semver"
              }
            ]
          }
        ],
        "source": "91579145-5d7b-4cc5-b925-a0262ff19630"
      }
    ],
    "cveTags": [],
    "descriptions": [
      {
        "lang": "en",
        "value": "Improper certificate validation in the directoryName name-constraint check (PkixNameConstraintValidator.WithinDNSubtree) in Legion of the Bouncy Castle Inc. bc-csharp before 2.7.0 allows an attacker who controls, or can have certificates issued by, a name-constrained intermediate CA to get certificates accepted by PKIX path validation whose subject distinguished name, or a directoryName subjectAltName, lies outside the CA's permitted subtrees, via a name that places other RDNs ahead of a copy of the permitted RDN sequence, because the check looks for the constraint's first RDN anywhere in the name and compares the remaining RDNs from that position, instead of requiring the constraint to be an initial prefix of the name as RFC 5280 sections 4.2.1.10 and 7.1 require."
      }
    ],
    "id": "CVE-2026-63577",
    "lastModified": "2026-10-02T14:44:52.247",
    "metrics": {
      "cvssMetricV40": [
        {
          "cvssData": {
            "Automatable": "NOT_DEFINED",
            "Recovery": "NOT_DEFINED",
            "Safety": "NOT_DEFINED",
            "attackComplexity": "LOW",
            "attackRequirements": "PRESENT",
            "attackVector": "NETWORK",
            "availabilityRequirement": "NOT_DEFINED",
            "baseScore": 8.2,
            "baseSeverity": "HIGH",
            "confidentialityRequirement": "NOT_DEFINED",
            "exploitMaturity": "NOT_DEFINED",
            "integrityRequirement": "NOT_DEFINED",
            "modifiedAttackComplexity": "NOT_DEFINED",
            "modifiedAttackRequirements": "NOT_DEFINED",
            "modifiedAttackVector": "NOT_DEFINED",
            "modifiedPrivilegesRequired": "NOT_DEFINED",
            "modifiedSubAvailabilityImpact": "NOT_DEFINED",
            "modifiedSubConfidentialityImpact": "NOT_DEFINED",
            "modifiedSubIntegrityImpact": "NOT_DEFINED",
            "modifiedUserInteraction": "NOT_DEFINED",
            "modifiedVulnAvailabilityImpact": "NOT_DEFINED",
            "modifiedVulnConfidentialityImpact": "NOT_DEFINED",
            "modifiedVulnIntegrityImpact": "NOT_DEFINED",
            "privilegesRequired": "NONE",
            "providerUrgency": "NOT_DEFINED",
            "subAvailabilityImpact": "NONE",
            "subConfidentialityImpact": "NONE",
            "subIntegrityImpact": "NONE",
            "userInteraction": "NONE",
            "valueDensity": "NOT_DEFINED",
            "vectorString": "CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:N/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:X",
            "version": "4.0",
            "vulnAvailabilityImpact": "NONE",
            "vulnConfidentialityImpact": "NONE",
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          "source": "91579145-5d7b-4cc5-b925-a0262ff19630",
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    },
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    "references": [
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      {
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      },
      {
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        "url": "https://github.com/bcgit/bc-csharp/wiki/CVE-2026-63577"
      }
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    "sourceIdentifier": "91579145-5d7b-4cc5-b925-a0262ff19630",
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            "value": "CWE-295"
          }
        ],
        "source": "91579145-5d7b-4cc5-b925-a0262ff19630",
        "type": "Secondary"
      }
    ]
  }
}

Text

Improper certificate validation in the directoryName name-constraint check (PkixNameConstraintValidator.WithinDNSubtree) in Legion of the Bouncy Castle Inc. bc-csharp before 2.7.0 allows an attacker who controls, or can have certificates issued by, a name-constrained intermediate CA to get certificates accepted by PKIX path validation whose subject distinguished name, or a directoryName subjectAltName, lies outside the CA's permitted subtrees, via a name that places other RDNs ahead of a copy of the permitted RDN sequence, because the check looks for the constraint's first RDN anywhere in the name and compares the remaining RDNs from that position, instead of requiring the constraint to be an initial prefix of the name as RFC 5280 sections 4.2.1.10 and 7.1 require.