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PKIXCertPathReviewer does not apply X.509 name constraints to the target certificate

Type: advisorySource: Official CVE List1 source record

In Bouncy Castle for Java before 1.86, neither copy of PKIXCertPathReviewer - org.bouncycastle.pkix.jcajce.PKIXCertPathReviewer nor the legacy org.bouncycastle.x509.PKIXCertPathReviewer - applied X.509 name constraints to the end-entity certificate. checkNameConstraints walked the path with a loop bound of index greater than zero, which is the bound the CA-only steps require, but index zero is the target certificate under the standard CertPath ordering, so the permitted and excluded subtree checks of RFC 5280 sec. 6.1.3 (b) and (c) never ran against the leaf's subject DN or its subjectAltName. A chain whose leaf violated a NameConstraints extension imposed by its own issuing CA therefore reported isValidCertPath() true with an empty error list, while CertPathValidator.getInstance("PKIX", "BC"), which shares no code with the reviewer, rejected the identical chain against the identical trust anchor. An application using the reviewer to make the trust decision rather than for diagnostics alongside a real validation accepted a certificate the constrained CA was never authorised to issue. Both copies now check every certificate in the path including the target, waive the sec. 4.2.1.10 self-issued exemption for the final certificate as sec. 6.1.3 requires, and skip the sec. 6.1.4 (g) constraint-accumulation step for the target. This issue also affects Bouncy Castle for Java LTS before 2.73.13, which carries only the org.bouncycastle.pkix.jcajce copy of the reviewer. It also affects

Announced Source revision 1
Original source ↗

CVE-2026-71889

Primary source · Revision 1

Imported from structured advisory data. Source references identify upstream records or fields; verify affected versions and your deployed configuration.

Security context

Source reference: cve:CVE-2026-71889

BC-JAVA

Source reference: /containers/cna/affected/0/product

Affected versions
Not stated in this record
Fixed versions
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Prerequisites
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BC-JAVA

Source reference: /containers/cna/affected/1/product

Affected versions
Not stated in this record
Fixed versions
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Prerequisites
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BC-LTS-JAVA

Source reference: /containers/cna/affected/2/product

Affected versions
Not stated in this record
Fixed versions
Not stated in this record
Prerequisites
Not stated in this record

BC-FJA

Source reference: /containers/cna/affected/3/product

Affected versions
Not stated in this record
Fixed versions
Not stated in this record
Prerequisites
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Structured affected-version data

Original package identities and version rules from this source.

[
  {
    "repo": "https://github.com/bcgit/bc-java",
    "vendor": "Legion of the Bouncy Castle Inc.",
    "modules": [
      "pkix"
    ],
    "product": "BC-JAVA",
    "versions": [
      {
        "status": "affected",
        "version": "0",
        "lessThan": "1.86",
        "versionType": "maven"
      }
    ],
    "platforms": [
      "all"
    ],
    "packageURL": "pkg:maven/org.bouncycastle/bcpkix-jdk18on",
    "packageName": "bcpkix",
    "programFiles": [
      "PKIXCertPathReviewer"
    ],
    "collectionURL": "https://www.bouncycastle.org/download/bouncy-castle-java/",
    "defaultStatus": "unaffected"
  },
  {
    "repo": "https://github.com/bcgit/bc-java",
    "vendor": "Legion of the Bouncy Castle Inc.",
    "modules": [
      "prov"
    ],
    "product": "BC-JAVA",
    "versions": [
      {
        "status": "affected",
        "version": "0",
        "lessThan": "1.86",
        "versionType": "maven"
      }
    ],
    "platforms": [
      "all"
    ],
    "packageURL": "pkg:maven/org.bouncycastle/bcprov-jdk18on",
    "packageName": "bcprov",
    "programFiles": [
      "PKIXCertPathReviewer"
    ],
    "collectionURL": "https://www.bouncycastle.org/download/bouncy-castle-java/",
    "defaultStatus": "unaffected"
  },
  {
    "repo": "https://github.com/bcgit/bc-lts-java",
    "vendor": "Legion of the Bouncy Castle Inc.",
    "modules": [
      "pkix"
    ],
    "product": "BC-LTS-JAVA",
    "versions": [
      {
        "status": "affected",
        "version": "2.73.0",
        "lessThan": "2.73.13",
        "versionType": "maven"
      }
    ],
    "platforms": [
      "all"
    ],
    "packageURL": "pkg:maven/org.bouncycastle/bcpkix-lts8on",
    "packageName": "bcpkix-lts8on",
    "programFiles": [
      "PKIXCertPathReviewer"
    ],
    "collectionURL": "https://www.bouncycastle.org/download/bouncy-castle-java-lts/",
    "defaultStatus": "unaffected"
  },
  {
    "vendor": "Legion of the Bouncy Castle Inc.",
    "product": "BC-FJA",
    "versions": [
      {
        "status": "affected",
        "version": "1.0.4",
        "lessThan": "1.0.13",
        "versionType": "maven"
      },
      {
        "status": "affected",
        "version": "2.0.0",
        "lessThan": "2.0.13",
        "versionType": "maven"
      },
      {
        "status": "affected",
        "version": "2.1.0",
        "lessThan": "2.1.13",
        "versionType": "maven"
      }
    ],
    "platforms": [
      "all"
    ],
    "packageURL": "pkg:maven/org.bouncycastle/bcpkix-fips",
    "packageName": "bcpkix-fips",
    "collectionURL": "https://www.bouncycastle.org/download/bouncy-castle-java-fips/",
    "defaultStatus": "unaffected"
  }
]
Related CVEs
CVE-2026-71889

Source reference: /cveMetadata/cveId

Publisher severity

high

Source reference: /containers/cna/metrics

Event
#8802 · Revision 1
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Publisher date
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