CVE-2026-5588 (GCVE-0-2026-5588)

Vulnerability from cvelistv5 – Published: 2026-04-15 09:06 – Updated: 2026-05-18 23:22
VLAI
Title
PKIX draft CompositeVerifier accepts empty signature sequence as valid.
Summary
Use of a Broken or Risky Cryptographic Algorithm vulnerability in Legion of the Bouncy Castle Inc. BC-JAVA bcpkix on all (pkix modules), Legion of the Bouncy Castle Inc. BCPKIX-FIPS bcpkix on All (pkix modules), Legion of the Bouncy Castle Inc. BCPIX-LTS bcpkix on All (pkix modules). This vulnerability is associated with program files JcaContentVerifierProviderBuilder.Java, JcaContentVerfierProviderBuilder.Java. This issue affects BC-JAVA: from 1.67 before 1.80.2, from 1.81 before 1.81.1, from 1.82 before 1.84; BCPKIX-FIPS: from 2.0.6 before 2.0.11, from 2.1.7 before 2.1.11; BCPIX-LTS: from 2.73.7 before 2.73.11.
Severity
6.3 (Medium)
CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:L/VI:N/VA:N/SC:N/SI:N/SA:N/U:Amber
SSVC
Exploitation: none Automatable: yes Technical Impact: partial
CISA Coordinator (v2.0.3)
CWE
  • CWE-327 - Use of a Broken or Risky Cryptographic Algorithm
Assigner
References
Impacted products
Vendor Product Version
Legion of the Bouncy Castle Inc. BC-JAVA Affected: 1.67 , < 1.80.2 (maven)
Affected: 1.81 , < 1.81.1 (maven)
Affected: 1.82 , < 1.84 (maven)
Create a notification for this product.
Legion of the Bouncy Castle Inc. BCPKIX-FIPS Affected: 2.0.6 , < 2.0.11 (maven)
Affected: 2.1.7 , < 2.1.11 (maven)
Create a notification for this product.
Legion of the Bouncy Castle Inc. BCPIX-LTS Affected: 2.73.7 , < 2.73.11 (maven)
Create a notification for this product.
Credits
Nicholas Carlini using Claude, Anthropic
Show details on NVD website
To clipboard 

{
  "containers": {
    "adp": [
      {
        "metrics": [
          {
            "other": {
              "content": {
                "id": "CVE-2026-5588",
                "options": [
                  {
                    "Exploitation": "none"
                  },
                  {
                    "Automatable": "yes"
                  },
                  {
                    "Technical Impact": "partial"
                  }
                ],
                "role": "CISA Coordinator",
                "timestamp": "2026-04-15T19:35:32.235455Z",
                "version": "2.0.3"
              },
              "type": "ssvc"
            }
          }
        ],
        "providerMetadata": {
          "dateUpdated": "2026-04-15T19:35:40.662Z",
          "orgId": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
          "shortName": "CISA-ADP"
        },
        "title": "CISA ADP Vulnrichment"
      }
    ],
    "cna": {
      "affected": [
        {
          "collectionURL": "https://www.bouncycastle.org/download/bouncy-castle-java/",
          "defaultStatus": "unaffected",
          "modules": [
            "pkix"
          ],
          "packageName": "bcpkix",
          "platforms": [
            "all"
          ],
          "product": "BC-JAVA",
          "programFiles": [
            "JcaContentVerifierProviderBuilder.java"
          ],
          "repo": "https://github.com/bcgit/bc-java",
          "vendor": "Legion of the Bouncy Castle Inc.",
          "versions": [
            {
              "lessThan": "1.80.2",
              "status": "affected",
              "version": "1.67",
              "versionType": "maven"
            },
            {
              "lessThan": "1.81.1",
              "status": "affected",
              "version": "1.81",
              "versionType": "maven"
            },
            {
              "lessThan": "1.84",
              "status": "affected",
              "version": "1.82",
              "versionType": "maven"
            }
          ]
        },
        {
          "collectionURL": "https://www.bouncycastle.org/download/bouncy-castle-java-fips/",
          "defaultStatus": "unaffected",
          "modules": [
            "pkix"
          ],
          "packageName": "bcpkix",
          "platforms": [
            "All"
          ],
          "product": "BCPKIX-FIPS",
          "programFiles": [
            "JcaContentVerifierProviderBuilder.java"
          ],
          "repo": "https://repo1.maven.org/maven2/org/bouncycastle/bcpkix-fips/",
          "vendor": "Legion of the Bouncy Castle Inc.",
          "versions": [
            {
              "lessThan": "2.0.11",
              "status": "affected",
              "version": "2.0.6",
              "versionType": "maven"
            },
            {
              "lessThan": "2.1.11",
              "status": "affected",
              "version": "2.1.7",
              "versionType": "maven"
            }
          ]
        },
        {
          "collectionURL": "https://www.bouncycastle.org/download/bouncy-castle-java-lts/",
          "defaultStatus": "unaffected",
          "modules": [
            "pkix"
          ],
          "packageName": "bcpkix",
          "platforms": [
            "All"
          ],
          "product": "BCPIX-LTS",
          "programFiles": [
            "JcaContentVerfierProviderBuilder.java"
          ],
          "repo": "https://repo1.maven.org/maven2/org/bouncycastle/bcpkix-lts8on/",
          "vendor": "Legion of the Bouncy Castle Inc.",
          "versions": [
            {
              "lessThan": "2.73.11",
              "status": "affected",
              "version": "2.73.7",
              "versionType": "maven"
            }
          ]
        }
      ],
      "credits": [
        {
          "lang": "en",
          "type": "finder",
          "value": "Nicholas Carlini using Claude, Anthropic"
        }
      ],
      "descriptions": [
        {
          "lang": "en",
          "supportingMedia": [
            {
              "base64": false,
              "type": "text/html",
              "value": "Use of a Broken or Risky Cryptographic Algorithm vulnerability in Legion of the Bouncy Castle Inc. BC-JAVA bcpkix on all (pkix modules), Legion of the Bouncy Castle Inc. BCPKIX-FIPS bcpkix on All (pkix modules), Legion of the Bouncy Castle Inc. BCPIX-LTS bcpkix on All (pkix modules).\u003cp\u003e This vulnerability is associated with program files JcaContentVerifierProviderBuilder.Java, JcaContentVerfierProviderBuilder.Java.\u003c/p\u003e\u003cp\u003eThis issue affects BC-JAVA: from 1.67 before 1.80.2, from 1.81 before 1.81.1, from 1.82 before 1.84; BCPKIX-FIPS: from 2.0.6 before 2.0.11, from 2.1.7 before 2.1.11; BCPIX-LTS: from 2.73.7 before 2.73.11.\u003c/p\u003e"
            }
          ],
          "value": "Use of a Broken or Risky Cryptographic Algorithm vulnerability in Legion of the Bouncy Castle Inc. BC-JAVA bcpkix on all (pkix modules), Legion of the Bouncy Castle Inc. BCPKIX-FIPS bcpkix on All (pkix modules), Legion of the Bouncy Castle Inc. BCPIX-LTS bcpkix on All (pkix modules).\n\n This vulnerability is associated with program files JcaContentVerifierProviderBuilder.Java, JcaContentVerfierProviderBuilder.Java.\n\n\n\nThis issue affects BC-JAVA: from 1.67 before 1.80.2, from 1.81 before 1.81.1, from 1.82 before 1.84; BCPKIX-FIPS: from 2.0.6 before 2.0.11, from 2.1.7 before 2.1.11; BCPIX-LTS: from 2.73.7 before 2.73.11."
        }
      ],
      "metrics": [
        {
          "cvssV4_0": {
            "Automatable": "NOT_DEFINED",
            "Recovery": "NOT_DEFINED",
            "Safety": "NOT_DEFINED",
            "attackComplexity": "LOW",
            "attackRequirements": "PRESENT",
            "attackVector": "NETWORK",
            "baseScore": 6.3,
            "baseSeverity": "MEDIUM",
            "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:P/PR:N/UI:N/VC:L/VI:N/VA:N/SC:N/SI:N/SA:N/U:Amber",
            "version": "4.0",
            "vulnAvailabilityImpact": "NONE",
            "vulnConfidentialityImpact": "LOW",
            "vulnIntegrityImpact": "NONE",
            "vulnerabilityResponseEffort": "NOT_DEFINED"
          },
          "format": "CVSS",
          "scenarios": [
            {
              "lang": "en",
              "value": "GENERAL"
            }
          ]
        }
      ],
      "problemTypes": [
        {
          "descriptions": [
            {
              "cweId": "CWE-327",
              "description": "CWE-327 Use of a Broken or Risky Cryptographic Algorithm",
              "lang": "en",
              "type": "CWE"
            }
          ]
        }
      ],
      "providerMetadata": {
        "dateUpdated": "2026-05-18T23:22:57.378Z",
        "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%905588"
        },
        {
          "tags": [
            "patch"
          ],
          "url": "https://github.com/bcgit/bc-java/commit/656bae0dbd9b1521f840521ff786e78749fe3057"
        }
      ],
      "source": {
        "discovery": "UNKNOWN"
      },
      "title": "PKIX draft CompositeVerifier accepts empty signature sequence as valid.",
      "x_generator": {
        "engine": "Vulnogram 1.0.1"
      }
    }
  },
  "cveMetadata": {
    "assignerOrgId": "91579145-5d7b-4cc5-b925-a0262ff19630",
    "assignerShortName": "bcorg",
    "cveId": "CVE-2026-5588",
    "datePublished": "2026-04-15T09:06:15.617Z",
    "dateReserved": "2026-04-04T23:50:59.336Z",
    "dateUpdated": "2026-05-18T23:22:57.378Z",
    "state": "PUBLISHED"
  },
  "dataType": "CVE_RECORD",
  "dataVersion": "5.2",
  "vulnerability-lookup:meta": {
    "epss": {
      "cve": "CVE-2026-5588",
      "date": "2026-06-19",
      "epss": "0.00259",
      "percentile": "0.17065"
    },
    "nvd": "{\"cve\":{\"id\":\"CVE-2026-5588\",\"sourceIdentifier\":\"91579145-5d7b-4cc5-b925-a0262ff19630\",\"published\":\"2026-04-15T10:16:49.597\",\"lastModified\":\"2026-05-19T00:16:37.613\",\"vulnStatus\":\"Awaiting Analysis\",\"cveTags\":[],\"descriptions\":[{\"lang\":\"en\",\"value\":\"Use of a Broken or Risky Cryptographic Algorithm vulnerability in Legion of the Bouncy Castle Inc. BC-JAVA bcpkix on all (pkix modules), Legion of the Bouncy Castle Inc. BCPKIX-FIPS bcpkix on All (pkix modules), Legion of the Bouncy Castle Inc. BCPIX-LTS bcpkix on All (pkix modules).\\n\\n This vulnerability is associated with program files JcaContentVerifierProviderBuilder.Java, JcaContentVerfierProviderBuilder.Java.\\n\\n\\n\\nThis issue affects BC-JAVA: from 1.67 before 1.80.2, from 1.81 before 1.81.1, from 1.82 before 1.84; BCPKIX-FIPS: from 2.0.6 before 2.0.11, from 2.1.7 before 2.1.11; BCPIX-LTS: from 2.73.7 before 2.73.11.\"}],\"metrics\":{\"cvssMetricV40\":[{\"source\":\"91579145-5d7b-4cc5-b925-a0262ff19630\",\"type\":\"Secondary\",\"cvssData\":{\"version\":\"4.0\",\"vectorString\":\"CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:L/VI:N/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\":6.3,\"baseSeverity\":\"MEDIUM\",\"attackVector\":\"NETWORK\",\"attackComplexity\":\"LOW\",\"attackRequirements\":\"PRESENT\",\"privilegesRequired\":\"NONE\",\"userInteraction\":\"NONE\",\"vulnConfidentialityImpact\":\"LOW\",\"vulnIntegrityImpact\":\"NONE\",\"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-327\"}]}],\"references\":[{\"url\":\"https://github.com/bcgit/bc-java/commit/656bae0dbd9b1521f840521ff786e78749fe3057\",\"source\":\"91579145-5d7b-4cc5-b925-a0262ff19630\"},{\"url\":\"https://github.com/bcgit/bc-java/wiki/CVE%E2%80%902026%E2%80%905588\",\"source\":\"91579145-5d7b-4cc5-b925-a0262ff19630\"}]}}",
    "vulnrichment": {
      "containers": "{\"adp\": [{\"title\": \"CISA ADP Vulnrichment\", \"metrics\": [{\"other\": {\"type\": \"ssvc\", \"content\": {\"id\": \"CVE-2026-5588\", \"role\": \"CISA Coordinator\", \"options\": [{\"Exploitation\": \"none\"}, {\"Automatable\": \"yes\"}, {\"Technical Impact\": \"partial\"}], \"version\": \"2.0.3\", \"timestamp\": \"2026-04-15T19:35:32.235455Z\"}}}], \"providerMetadata\": {\"orgId\": \"134c704f-9b21-4f2e-91b3-4a467353bcc0\", \"shortName\": \"CISA-ADP\", \"dateUpdated\": \"2026-04-15T13:11:21.652Z\"}}], \"cna\": {\"title\": \"PKIX draft CompositeVerifier accepts empty signature sequence as valid.\", \"source\": {\"discovery\": \"UNKNOWN\"}, \"credits\": [{\"lang\": \"en\", \"type\": \"finder\", \"value\": \"Nicholas Carlini using Claude, Anthropic\"}], \"metrics\": [{\"format\": \"CVSS\", \"cvssV4_0\": {\"Safety\": \"NOT_DEFINED\", \"version\": \"4.0\", \"Recovery\": \"NOT_DEFINED\", \"baseScore\": 6.3, \"Automatable\": \"NOT_DEFINED\", \"attackVector\": \"NETWORK\", \"baseSeverity\": \"MEDIUM\", \"valueDensity\": \"NOT_DEFINED\", \"vectorString\": \"CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:L/VI:N/VA:N/SC:N/SI:N/SA:N/U:Amber\", \"exploitMaturity\": \"NOT_DEFINED\", \"providerUrgency\": \"AMBER\", \"userInteraction\": \"NONE\", \"attackComplexity\": \"LOW\", \"attackRequirements\": \"PRESENT\", \"privilegesRequired\": \"NONE\", \"subIntegrityImpact\": \"NONE\", \"vulnIntegrityImpact\": \"NONE\", \"subAvailabilityImpact\": \"NONE\", \"vulnAvailabilityImpact\": \"NONE\", \"subConfidentialityImpact\": \"NONE\", \"vulnConfidentialityImpact\": \"LOW\", \"vulnerabilityResponseEffort\": \"NOT_DEFINED\"}, \"scenarios\": [{\"lang\": \"en\", \"value\": \"GENERAL\"}]}], \"affected\": [{\"repo\": \"https://github.com/bcgit/bc-java\", \"vendor\": \"Legion of the Bouncy Castle Inc.\", \"modules\": [\"pkix\"], \"product\": \"BC-JAVA\", \"versions\": [{\"status\": \"affected\", \"version\": \"1.67\", \"lessThan\": \"1.80.2\", \"versionType\": \"maven\"}, {\"status\": \"affected\", \"version\": \"1.81\", \"lessThan\": \"1.81.1\", \"versionType\": \"maven\"}, {\"status\": \"affected\", \"version\": \"1.82\", \"lessThan\": \"1.84\", \"versionType\": \"maven\"}], \"platforms\": [\"all\"], \"packageName\": \"bcpkix\", \"programFiles\": [\"JcaContentVerifierProviderBuilder.java\"], \"collectionURL\": \"https://www.bouncycastle.org/download/bouncy-castle-java/\", \"defaultStatus\": \"unaffected\"}, {\"repo\": \"https://repo1.maven.org/maven2/org/bouncycastle/bcpkix-fips/\", \"vendor\": \"Legion of the Bouncy Castle Inc.\", \"modules\": [\"pkix\"], \"product\": \"BCPKIX-FIPS\", \"versions\": [{\"status\": \"affected\", \"version\": \"2.0.6\", \"lessThan\": \"2.0.11\", \"versionType\": \"maven\"}, {\"status\": \"affected\", \"version\": \"2.1.7\", \"lessThan\": \"2.1.11\", \"versionType\": \"maven\"}], \"platforms\": [\"All\"], \"packageName\": \"bcpkix\", \"programFiles\": [\"JcaContentVerifierProviderBuilder.java\"], \"collectionURL\": \"https://www.bouncycastle.org/download/bouncy-castle-java-fips/\", \"defaultStatus\": \"unaffected\"}, {\"repo\": \"https://repo1.maven.org/maven2/org/bouncycastle/bcpkix-lts8on/\", \"vendor\": \"Legion of the Bouncy Castle Inc.\", \"modules\": [\"pkix\"], \"product\": \"BCPIX-LTS\", \"versions\": [{\"status\": \"affected\", \"version\": \"2.73.7\", \"lessThan\": \"2.73.11\", \"versionType\": \"maven\"}], \"platforms\": [\"All\"], \"packageName\": \"bcpkix\", \"programFiles\": [\"JcaContentVerfierProviderBuilder.java\"], \"collectionURL\": \"https://www.bouncycastle.org/download/bouncy-castle-java-lts/\", \"defaultStatus\": \"unaffected\"}], \"references\": [{\"url\": \"https://github.com/bcgit/bc-java/wiki/CVE%E2%80%902026%E2%80%905588\", \"tags\": [\"vendor-advisory\"]}, {\"url\": \"https://github.com/bcgit/bc-java/commit/656bae0dbd9b1521f840521ff786e78749fe3057\", \"tags\": [\"patch\"]}], \"x_generator\": {\"engine\": \"Vulnogram 1.0.1\"}, \"descriptions\": [{\"lang\": \"en\", \"value\": \"Use of a Broken or Risky Cryptographic Algorithm vulnerability in Legion of the Bouncy Castle Inc. BC-JAVA bcpkix on all (pkix modules), Legion of the Bouncy Castle Inc. BCPKIX-FIPS bcpkix on All (pkix modules), Legion of the Bouncy Castle Inc. BCPIX-LTS bcpkix on All (pkix modules).\\n\\n This vulnerability is associated with program files JcaContentVerifierProviderBuilder.Java, JcaContentVerfierProviderBuilder.Java.\\n\\n\\n\\nThis issue affects BC-JAVA: from 1.67 before 1.80.2, from 1.81 before 1.81.1, from 1.82 before 1.84; BCPKIX-FIPS: from 2.0.6 before 2.0.11, from 2.1.7 before 2.1.11; BCPIX-LTS: from 2.73.7 before 2.73.11.\", \"supportingMedia\": [{\"type\": \"text/html\", \"value\": \"Use of a Broken or Risky Cryptographic Algorithm vulnerability in Legion of the Bouncy Castle Inc. BC-JAVA bcpkix on all (pkix modules), Legion of the Bouncy Castle Inc. BCPKIX-FIPS bcpkix on All (pkix modules), Legion of the Bouncy Castle Inc. BCPIX-LTS bcpkix on All (pkix modules).\u003cp\u003e This vulnerability is associated with program files JcaContentVerifierProviderBuilder.Java, JcaContentVerfierProviderBuilder.Java.\u003c/p\u003e\u003cp\u003eThis issue affects BC-JAVA: from 1.67 before 1.80.2, from 1.81 before 1.81.1, from 1.82 before 1.84; BCPKIX-FIPS: from 2.0.6 before 2.0.11, from 2.1.7 before 2.1.11; BCPIX-LTS: from 2.73.7 before 2.73.11.\u003c/p\u003e\", \"base64\": false}]}], \"problemTypes\": [{\"descriptions\": [{\"lang\": \"en\", \"type\": \"CWE\", \"cweId\": \"CWE-327\", \"description\": \"CWE-327 Use of a Broken or Risky Cryptographic Algorithm\"}]}], \"providerMetadata\": {\"orgId\": \"91579145-5d7b-4cc5-b925-a0262ff19630\", \"shortName\": \"bcorg\", \"dateUpdated\": \"2026-05-18T23:22:57.378Z\"}}}",
      "cveMetadata": "{\"cveId\": \"CVE-2026-5588\", \"state\": \"PUBLISHED\", \"dateUpdated\": \"2026-05-18T23:22:57.378Z\", \"dateReserved\": \"2026-04-04T23:50:59.336Z\", \"assignerOrgId\": \"91579145-5d7b-4cc5-b925-a0262ff19630\", \"datePublished\": \"2026-04-15T09:06:15.617Z\", \"assignerShortName\": \"bcorg\"}",
      "dataType": "CVE_RECORD",
      "dataVersion": "5.2"
    }
  }
}


Log in or create an account to share your comment.




Tags
Taxonomy of the tags.





Forecast uses a logistic model when the trend is rising, or an exponential decay model when the trend is falling. Fitted via linearized least squares.

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.