GCVE Workshop - 22 September 2026 (14:00-18:00), Luxembourg Before The Vulnopticon Conference - Registration

CVE-2026-54431 (GCVE-0-2026-54431)

Vulnerability from cvelistv5 – Published: 2026-07-02 10:30 – Updated: 2026-07-02 12:16 X_Open Source
VLAI
Title
Improper Data Validation in liboauth2
Summary
In liboauth2 the Demonstrating Proof-of-Possession (DPoP) verifier accepts a proof whose JSON Web Key (jwk) header contains private key material. RFC 9449 section 4.3 step 7 requires the verifier to reject such a proof but oauth2_token_verify() function returns success for a malformed DPoP proof that embeds the private Elliptic Curve (EC) key in the header. This issue was fixed in version 2.3.0
Severity
5.1 (Medium)
CVSS:4.0/AV:L/AC:L/AT:N/PR:N/UI:N/VC:L/VI:N/VA:N/SC:N/SI:N/SA:N
SSVC
Exploitation: none Automatable: no Technical Impact: partial
CISA Coordinator · CISA-ADP (v2.0.3)
Decision recorded 2026-07-02 12:16 UTC
CWE
  • CWE-358 - Improperly Implemented Security Check for Standard
Assigner
References
Impacted products
Vendor Product Version CPE status
OpenIDC liboauth2 Affected: 0 , < 2.3.0 (semver)
guessed Create a notification for this product.
Date Public
2026-07-02 00:00
Credits
Michał Majchrowicz (AFINE Team) Marcin Wyczechowski (AFINE Team)
Show details on NVD website
To clipboard 

{
  "containers": {
    "adp": [
      {
        "metrics": [
          {
            "other": {
              "content": {
                "id": "CVE-2026-54431",
                "options": [
                  {
                    "Exploitation": "none"
                  },
                  {
                    "Automatable": "no"
                  },
                  {
                    "Technical Impact": "partial"
                  }
                ],
                "role": "CISA Coordinator",
                "timestamp": "2026-07-02T12:16:34.432412Z",
                "version": "2.0.3"
              },
              "type": "ssvc"
            }
          }
        ],
        "providerMetadata": {
          "dateUpdated": "2026-07-02T12:16:41.569Z",
          "orgId": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
          "shortName": "CISA-ADP"
        },
        "title": "CISA ADP Vulnrichment"
      }
    ],
    "cna": {
      "affected": [
        {
          "defaultStatus": "unaffected",
          "product": "liboauth2",
          "programFiles": [
            "src/dpop.c"
          ],
          "programRoutines": [
            {
              "name": "_oauth2_dpop_parse_and_validate()"
            }
          ],
          "repo": "https://github.com/OpenIDC/liboauth2",
          "vendor": "OpenIDC",
          "versions": [
            {
              "lessThan": "2.3.0",
              "status": "affected",
              "version": "0",
              "versionType": "semver"
            }
          ]
        }
      ],
      "credits": [
        {
          "lang": "en",
          "type": "finder",
          "value": "Micha\u0142 Majchrowicz (AFINE Team)"
        },
        {
          "lang": "en",
          "type": "finder",
          "value": "Marcin Wyczechowski (AFINE Team)"
        }
      ],
      "datePublic": "2026-07-02T00:00:00.000Z",
      "descriptions": [
        {
          "lang": "en",
          "supportingMedia": [
            {
              "base64": false,
              "type": "text/html",
              "value": "\u003cspan\u003eIn liboauth2 the Demonstrating Proof-of-Possession (DPoP) verifier accepts a proof whose JSON Web Key (jwk) header contains private key\u0026nbsp;\u003c/span\u003e\u003cspan\u003ematerial. RFC 9449 section 4.3 step 7 requires the verifier to reject\u0026nbsp;\u003c/span\u003e\u003cspan\u003esuch a proof but\u003c/span\u003e\u003cspan\u003e\u0026nbsp;\u003ci\u003eoauth2_token_verify()\u003c/i\u003e function returns success for a malformed DPoP\u0026nbsp;\u003c/span\u003e\u003cspan\u003eproof that embeds the private Elliptic Curve (EC) key in the header.\u003cbr\u003e\u003cbr\u003e\u003c/span\u003eThis issue was fixed in version 2.3.0"
            }
          ],
          "value": "In liboauth2 the Demonstrating Proof-of-Possession (DPoP) verifier accepts a proof whose JSON Web Key (jwk) header contains private key\u00a0material. RFC 9449 section 4.3 step 7 requires the verifier to reject\u00a0such a proof but\u00a0oauth2_token_verify() function returns success for a malformed DPoP\u00a0proof that embeds the private Elliptic Curve (EC) key in the header.\n\nThis issue was fixed in version 2.3.0"
        }
      ],
      "metrics": [
        {
          "cvssV4_0": {
            "Automatable": "NOT_DEFINED",
            "Recovery": "NOT_DEFINED",
            "Safety": "NOT_DEFINED",
            "attackComplexity": "LOW",
            "attackRequirements": "NONE",
            "attackVector": "LOCAL",
            "baseScore": 5.1,
            "baseSeverity": "MEDIUM",
            "exploitMaturity": "NOT_DEFINED",
            "privilegesRequired": "NONE",
            "providerUrgency": "NOT_DEFINED",
            "subAvailabilityImpact": "NONE",
            "subConfidentialityImpact": "NONE",
            "subIntegrityImpact": "NONE",
            "userInteraction": "NONE",
            "valueDensity": "NOT_DEFINED",
            "vectorString": "CVSS:4.0/AV:L/AC:L/AT:N/PR:N/UI:N/VC:L/VI:N/VA:N/SC:N/SI:N/SA:N",
            "version": "4.0",
            "vulnAvailabilityImpact": "NONE",
            "vulnConfidentialityImpact": "LOW",
            "vulnIntegrityImpact": "NONE",
            "vulnerabilityResponseEffort": "NOT_DEFINED"
          },
          "format": "CVSS",
          "scenarios": [
            {
              "lang": "en",
              "value": "GENERAL"
            }
          ]
        }
      ],
      "problemTypes": [
        {
          "descriptions": [
            {
              "cweId": "CWE-358",
              "description": "CWE-358 Improperly Implemented Security Check for Standard",
              "lang": "en",
              "type": "CWE"
            }
          ]
        }
      ],
      "providerMetadata": {
        "dateUpdated": "2026-07-02T10:44:44.691Z",
        "orgId": "4bb8329e-dd38-46c1-aafb-9bf32bcb93c6",
        "shortName": "CERT-PL"
      },
      "references": [
        {
          "tags": [
            "third-party-advisory"
          ],
          "url": "https://cert.pl/en/posts/2026/07/CVE-2026-54430"
        },
        {
          "tags": [
            "product"
          ],
          "url": "https://github.com/OpenIDC/liboauth2"
        },
        {
          "tags": [
            "issue-tracking"
          ],
          "url": "https://github.com/OpenIDC/liboauth2/commit/c0b57152ed6a0af33aeb04a60bd7f5bff5ab8800"
        }
      ],
      "source": {
        "discovery": "EXTERNAL"
      },
      "tags": [
        "x_open-source"
      ],
      "title": "Improper Data Validation in liboauth2",
      "x_generator": {
        "engine": "Vulnogram 0.2.0"
      }
    }
  },
  "cveMetadata": {
    "assignerOrgId": "4bb8329e-dd38-46c1-aafb-9bf32bcb93c6",
    "assignerShortName": "CERT-PL",
    "cveId": "CVE-2026-54431",
    "datePublished": "2026-07-02T10:30:57.655Z",
    "dateReserved": "2026-06-15T13:08:01.057Z",
    "dateUpdated": "2026-07-02T12:16:41.569Z",
    "state": "PUBLISHED"
  },
  "dataType": "CVE_RECORD",
  "dataVersion": "5.2",
  "vulnerability-lookup:meta": {
    "epss": {
      "cve": "CVE-2026-54431",
      "date": "2026-09-15",
      "epss": "0.00178",
      "percentile": "0.07551"
    },
    "nvd": "{\"cve\":{\"id\":\"CVE-2026-54431\",\"sourceIdentifier\":\"cvd@cert.pl\",\"published\":\"2026-07-02T11:16:17.123\",\"lastModified\":\"2026-07-02T17:43:14.020\",\"vulnStatus\":\"Deferred\",\"cveTags\":[],\"descriptions\":[{\"lang\":\"en\",\"value\":\"In liboauth2 the Demonstrating Proof-of-Possession (DPoP) verifier accepts a proof whose JSON Web Key (jwk) header contains private key\u00a0material. RFC 9449 section 4.3 step 7 requires the verifier to reject\u00a0such a proof but\u00a0oauth2_token_verify() function returns success for a malformed DPoP\u00a0proof that embeds the private Elliptic Curve (EC) key in the header.\\n\\nThis issue was fixed in version 2.3.0\"}],\"affected\":[{\"source\":\"cvd@cert.pl\",\"affectedData\":[{\"vendor\":\"OpenIDC\",\"product\":\"liboauth2\",\"defaultStatus\":\"unaffected\",\"programFiles\":[\"src/dpop.c\"],\"programRoutines\":[{\"name\":\"_oauth2_dpop_parse_and_validate()\"}],\"repo\":\"https://github.com/OpenIDC/liboauth2\",\"versions\":[{\"version\":\"0\",\"lessThan\":\"2.3.0\",\"versionType\":\"semver\",\"status\":\"affected\"}]}]}],\"metrics\":{\"cvssMetricV40\":[{\"source\":\"cvd@cert.pl\",\"type\":\"Secondary\",\"cvssData\":{\"version\":\"4.0\",\"vectorString\":\"CVSS:4.0/AV:L/AC:L/AT:N/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:X\",\"baseScore\":5.1,\"baseSeverity\":\"MEDIUM\",\"attackVector\":\"LOCAL\",\"attackComplexity\":\"LOW\",\"attackRequirements\":\"NONE\",\"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\":\"NOT_DEFINED\"}}],\"ssvcV203\":[{\"source\":\"134c704f-9b21-4f2e-91b3-4a467353bcc0\",\"ssvcData\":{\"timestamp\":\"2026-07-02T12:16:34.432412Z\",\"id\":\"CVE-2026-54431\",\"options\":[{\"exploitation\":\"none\"},{\"automatable\":\"no\"},{\"technicalImpact\":\"partial\"}],\"role\":\"CISA Coordinator\",\"version\":\"2.0.3\"}}]},\"weaknesses\":[{\"source\":\"cvd@cert.pl\",\"type\":\"Secondary\",\"description\":[{\"lang\":\"en\",\"value\":\"CWE-358\"}]}],\"references\":[{\"url\":\"https://cert.pl/en/posts/2026/07/CVE-2026-54430\",\"source\":\"cvd@cert.pl\"},{\"url\":\"https://github.com/OpenIDC/liboauth2\",\"source\":\"cvd@cert.pl\"},{\"url\":\"https://github.com/OpenIDC/liboauth2/commit/c0b57152ed6a0af33aeb04a60bd7f5bff5ab8800\",\"source\":\"cvd@cert.pl\"}]}}",
    "redhat_vex": {
      "current_release_date": "2026-07-03T02:35:48+00:00",
      "cve": "CVE-2026-54431",
      "id": "CVE-2026-54431",
      "initial_release_date": "2026-07-02T10:30:57.655000+00:00",
      "product_status:known_not_affected": "1",
      "source": "Red Hat CSAF VEX",
      "status": "final",
      "title": "liboauth2: liboauth2: DPoP verifier accepts malformed proof with private key material",
      "url": "https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-54431.json",
      "version": "3"
    },
    "vulnrichment": {
      "containers": "{\"adp\": [{\"title\": \"CISA ADP Vulnrichment\", \"metrics\": [{\"other\": {\"type\": \"ssvc\", \"content\": {\"id\": \"CVE-2026-54431\", \"role\": \"CISA Coordinator\", \"options\": [{\"Exploitation\": \"none\"}, {\"Automatable\": \"no\"}, {\"Technical Impact\": \"partial\"}], \"version\": \"2.0.3\", \"timestamp\": \"2026-07-02T12:16:34.432412Z\"}}}], \"providerMetadata\": {\"orgId\": \"134c704f-9b21-4f2e-91b3-4a467353bcc0\", \"shortName\": \"CISA-ADP\", \"dateUpdated\": \"2026-07-02T12:16:37.310Z\"}}], \"cna\": {\"tags\": [\"x_open-source\"], \"title\": \"Improper Data Validation in liboauth2\", \"source\": {\"discovery\": \"EXTERNAL\"}, \"credits\": [{\"lang\": \"en\", \"type\": \"finder\", \"value\": \"Micha\\u0142 Majchrowicz (AFINE Team)\"}, {\"lang\": \"en\", \"type\": \"finder\", \"value\": \"Marcin Wyczechowski (AFINE Team)\"}], \"metrics\": [{\"format\": \"CVSS\", \"cvssV4_0\": {\"Safety\": \"NOT_DEFINED\", \"version\": \"4.0\", \"Recovery\": \"NOT_DEFINED\", \"baseScore\": 5.1, \"Automatable\": \"NOT_DEFINED\", \"attackVector\": \"LOCAL\", \"baseSeverity\": \"MEDIUM\", \"valueDensity\": \"NOT_DEFINED\", \"vectorString\": \"CVSS:4.0/AV:L/AC:L/AT:N/PR:N/UI:N/VC:L/VI:N/VA:N/SC:N/SI:N/SA:N\", \"exploitMaturity\": \"NOT_DEFINED\", \"providerUrgency\": \"NOT_DEFINED\", \"userInteraction\": \"NONE\", \"attackComplexity\": \"LOW\", \"attackRequirements\": \"NONE\", \"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/OpenIDC/liboauth2\", \"vendor\": \"OpenIDC\", \"product\": \"liboauth2\", \"versions\": [{\"status\": \"affected\", \"version\": \"0\", \"lessThan\": \"2.3.0\", \"versionType\": \"semver\"}], \"programFiles\": [\"src/dpop.c\"], \"defaultStatus\": \"unaffected\", \"programRoutines\": [{\"name\": \"_oauth2_dpop_parse_and_validate()\"}]}], \"datePublic\": \"2026-07-02T00:00:00.000Z\", \"references\": [{\"url\": \"https://cert.pl/en/posts/2026/07/CVE-2026-54430\", \"tags\": [\"third-party-advisory\"]}, {\"url\": \"https://github.com/OpenIDC/liboauth2\", \"tags\": [\"product\"]}, {\"url\": \"https://github.com/OpenIDC/liboauth2/commit/c0b57152ed6a0af33aeb04a60bd7f5bff5ab8800\", \"tags\": [\"issue-tracking\"]}], \"x_generator\": {\"engine\": \"Vulnogram 0.2.0\"}, \"descriptions\": [{\"lang\": \"en\", \"value\": \"In liboauth2 the Demonstrating Proof-of-Possession (DPoP) verifier accepts a proof whose JSON Web Key (jwk) header contains private key\\u00a0material. RFC 9449 section 4.3 step 7 requires the verifier to reject\\u00a0such a proof but\\u00a0oauth2_token_verify() function returns success for a malformed DPoP\\u00a0proof that embeds the private Elliptic Curve (EC) key in the header.\\n\\nThis issue was fixed in version 2.3.0\", \"supportingMedia\": [{\"type\": \"text/html\", \"value\": \"\u003cspan\u003eIn liboauth2 the Demonstrating Proof-of-Possession (DPoP) verifier accepts a proof whose JSON Web Key (jwk) header contains private key\u0026nbsp;\u003c/span\u003e\u003cspan\u003ematerial. RFC 9449 section 4.3 step 7 requires the verifier to reject\u0026nbsp;\u003c/span\u003e\u003cspan\u003esuch a proof but\u003c/span\u003e\u003cspan\u003e\u0026nbsp;\u003ci\u003eoauth2_token_verify()\u003c/i\u003e function returns success for a malformed DPoP\u0026nbsp;\u003c/span\u003e\u003cspan\u003eproof that embeds the private Elliptic Curve (EC) key in the header.\u003cbr\u003e\u003cbr\u003e\u003c/span\u003eThis issue was fixed in version 2.3.0\", \"base64\": false}]}], \"problemTypes\": [{\"descriptions\": [{\"lang\": \"en\", \"type\": \"CWE\", \"cweId\": \"CWE-358\", \"description\": \"CWE-358 Improperly Implemented Security Check for Standard\"}]}], \"providerMetadata\": {\"orgId\": \"4bb8329e-dd38-46c1-aafb-9bf32bcb93c6\", \"shortName\": \"CERT-PL\", \"dateUpdated\": \"2026-07-02T10:44:44.691Z\"}}}",
      "cveMetadata": "{\"cveId\": \"CVE-2026-54431\", \"state\": \"PUBLISHED\", \"dateUpdated\": \"2026-07-02T12:16:41.569Z\", \"dateReserved\": \"2026-06-15T13:08:01.057Z\", \"assignerOrgId\": \"4bb8329e-dd38-46c1-aafb-9bf32bcb93c6\", \"datePublished\": \"2026-07-02T10:30:57.655Z\", \"assignerShortName\": \"CERT-PL\"}",
      "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.


Related by attack behaviour

Vulnerabilities whose description is nearest to this one in the vector space of the CIRCL/vulnerability-attack-technique-biencoder model. This is a similarity search over the bi-encoder space (plain cosine), not a classification, and it has no measured accuracy.