FKIE_CVE-2026-75759

Vulnerability from fkie_nvd - Published: 2026-08-30 02:18 - Updated: 2026-08-30 02:18
Severity
7.6 (High) - CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:P/VC:H/VI:H/VA:N/SC:N/SI:N/SA:N
Summary
Improper Verification of Cryptographic Signature vulnerability in erlef oidcc allows an unauthenticated attacker to impersonate an arbitrary user via an encrypted ID token or JARM response carrying no nested signature. OpenID Connect Core 1.0 section 2 requires that an encrypted ID token be signed then encrypted, with the result being a Nested JWT, and JARM processing rule 5 requires the client to check the signature unconditionally. oidcc instead accepted a JWE wrapping unsigned claims as fully validated, so anyone holding the relying party's public encryption key could mint a token with an arbitrary sub, iss, and aud without possessing the provider's signing key. In oidcc_jwt_util:verify_decrypted_token/4, a decrypted payload that is not a signed JWS fell back to parsing the plaintext claims and returning them with no verifying key. oidcc_token:int_validate_jwt/4 then matched on the JOSE structure type rather than on whether a signature had been verified, and returned success. The JARM path in oidcc_token:validate_jarm/3 is reachable through the browser front channel. UserInfo responses are not affected, because OpenID Connect Core 1.0 section 5.3.2 permits them to be encrypted without also being signed. This issue affects oidcc: from 3.2.0-beta.1 before 3.9.0.
References
6b3ad84c-e1a6-4bf7-a703-f496b71e49dbhttps://cna.erlef.org/cves/CVE-2026-75759.html
6b3ad84c-e1a6-4bf7-a703-f496b71e49dbhttps://github.com/erlef/oidcc/commit/5f62fbccdae8526ff62653b8901657a6c1400fd9
6b3ad84c-e1a6-4bf7-a703-f496b71e49dbhttps://github.com/erlef/oidcc/security/advisories/GHSA-533g-4vf3-xwrj
6b3ad84c-e1a6-4bf7-a703-f496b71e49dbhttps://osv.dev/vulnerability/EEF-CVE-2026-75759
Impacted products
Vendor Product Version
To clipboard 

{
  "affected": [
    {
      "affectedData": [
        {
          "collectionURL": "https://repo.hex.pm",
          "cpes": [
            "cpe:2.3:a:erlef:oidcc:*:*:*:*:*:*:*:*"
          ],
          "defaultStatus": "unaffected",
          "modules": [
            "oidcc_jwt_util",
            "oidcc_token"
          ],
          "packageName": "oidcc",
          "packageURL": "pkg:hex/oidcc",
          "product": "oidcc",
          "programFiles": [
            "src/oidcc_jwt_util.erl",
            "src/oidcc_token.erl"
          ],
          "programRoutines": [
            {
              "name": "oidcc_jwt_util:verify_decrypted_token/4"
            },
            {
              "name": "oidcc_jwt_util:verify_not_none_alg/1"
            },
            {
              "name": "oidcc_token:int_validate_jwt/4"
            },
            {
              "name": "oidcc_token:validate_id_token/3"
            },
            {
              "name": "oidcc_token:validate_jarm/3"
            }
          ],
          "repo": "https://github.com/erlef/oidcc",
          "vendor": "erlef",
          "versions": [
            {
              "lessThan": "3.9.0",
              "status": "affected",
              "version": "3.2.0-beta.1",
              "versionType": "semver"
            }
          ]
        },
        {
          "collectionURL": "https://github.com",
          "cpes": [
            "cpe:2.3:a:erlef:oidcc:*:*:*:*:*:*:*:*"
          ],
          "defaultStatus": "unaffected",
          "modules": [
            "oidcc_jwt_util",
            "oidcc_token"
          ],
          "packageName": "erlef/oidcc",
          "packageURL": "pkg:github/erlef/oidcc",
          "product": "oidcc",
          "programFiles": [
            "src/oidcc_jwt_util.erl",
            "src/oidcc_token.erl"
          ],
          "programRoutines": [
            {
              "name": "oidcc_jwt_util:verify_decrypted_token/4"
            },
            {
              "name": "oidcc_jwt_util:verify_not_none_alg/1"
            },
            {
              "name": "oidcc_token:int_validate_jwt/4"
            },
            {
              "name": "oidcc_token:validate_id_token/3"
            },
            {
              "name": "oidcc_token:validate_jarm/3"
            }
          ],
          "repo": "https://github.com/erlef/oidcc",
          "vendor": "erlef",
          "versions": [
            {
              "lessThan": "5f62fbccdae8526ff62653b8901657a6c1400fd9",
              "status": "affected",
              "version": "37a1361f704889816db2873f72d744d63ec39568",
              "versionType": "git"
            }
          ]
        }
      ],
      "source": "6b3ad84c-e1a6-4bf7-a703-f496b71e49db"
    }
  ],
  "cveTags": [],
  "descriptions": [
    {
      "lang": "en",
      "value": "Improper Verification of Cryptographic Signature vulnerability in erlef oidcc allows an unauthenticated attacker to impersonate an arbitrary user via an encrypted ID token or JARM response carrying no nested signature. OpenID Connect Core 1.0 section 2 requires that an encrypted ID token be signed then encrypted, with the result being a Nested JWT, and JARM processing rule 5 requires the client to check the signature unconditionally. oidcc instead accepted a JWE wrapping unsigned claims as fully validated, so anyone holding the relying party\u0027s public encryption key could mint a token with an arbitrary sub, iss, and aud without possessing the provider\u0027s signing key.\n\nIn oidcc_jwt_util:verify_decrypted_token/4, a decrypted payload that is not a signed JWS fell back to parsing the plaintext claims and returning them with no verifying key. oidcc_token:int_validate_jwt/4 then matched on the JOSE structure type rather than on whether a signature had been verified, and returned success. The JARM path in oidcc_token:validate_jarm/3 is reachable through the browser front channel. UserInfo responses are not affected, because OpenID Connect Core 1.0 section 5.3.2 permits them to be encrypted without also being signed.\n\nThis issue affects oidcc: from 3.2.0-beta.1 before 3.9.0."
    }
  ],
  "id": "CVE-2026-75759",
  "lastModified": "2026-08-30T02:18:30.110",
  "metrics": {
    "cvssMetricV40": [
      {
        "cvssData": {
          "Automatable": "NOT_DEFINED",
          "Recovery": "NOT_DEFINED",
          "Safety": "NOT_DEFINED",
          "attackComplexity": "LOW",
          "attackRequirements": "PRESENT",
          "attackVector": "NETWORK",
          "availabilityRequirement": "NOT_DEFINED",
          "baseScore": 7.6,
          "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": "PASSIVE",
          "valueDensity": "NOT_DEFINED",
          "vectorString": "CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:P/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:X",
          "version": "4.0",
          "vulnAvailabilityImpact": "NONE",
          "vulnConfidentialityImpact": "HIGH",
          "vulnIntegrityImpact": "HIGH",
          "vulnerabilityResponseEffort": "NOT_DEFINED"
        },
        "source": "6b3ad84c-e1a6-4bf7-a703-f496b71e49db",
        "type": "Secondary"
      }
    ]
  },
  "published": "2026-08-30T02:18:30.110",
  "references": [
    {
      "source": "6b3ad84c-e1a6-4bf7-a703-f496b71e49db",
      "url": "https://cna.erlef.org/cves/CVE-2026-75759.html"
    },
    {
      "source": "6b3ad84c-e1a6-4bf7-a703-f496b71e49db",
      "url": "https://github.com/erlef/oidcc/commit/5f62fbccdae8526ff62653b8901657a6c1400fd9"
    },
    {
      "source": "6b3ad84c-e1a6-4bf7-a703-f496b71e49db",
      "url": "https://github.com/erlef/oidcc/security/advisories/GHSA-533g-4vf3-xwrj"
    },
    {
      "source": "6b3ad84c-e1a6-4bf7-a703-f496b71e49db",
      "url": "https://osv.dev/vulnerability/EEF-CVE-2026-75759"
    }
  ],
  "sourceIdentifier": "6b3ad84c-e1a6-4bf7-a703-f496b71e49db",
  "vulnStatus": "Received",
  "weaknesses": [
    {
      "description": [
        {
          "lang": "en",
          "value": "CWE-347"
        }
      ],
      "source": "6b3ad84c-e1a6-4bf7-a703-f496b71e49db",
      "type": "Secondary"
    }
  ]
}



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