FKIE_CVE-2026-34182

Vulnerability from fkie_nvd - Published: 2026-06-09 17:17 - Updated: 2026-06-10 17:16
Severity
9.1 (Critical) - CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N
Summary
Issue Summary: Cryptographic Message Services (CMS) processing fails to perform sufficient input validation on the cipher and tag length fields of AuthEnvelopedData containers, leading to various potential compromises. Impact Summary: Attackers making use of these vulnerabilities may achieve key-equivalent functionality for a given CMS recipient and/or bypass integrity validation for a given message. In one use case, an attacker may send a CMS message containing AuthEnvelopedData with the cipher specified as a non-AEAD cipher. OpenSSL erroneously allows this selection, and attempts to decrypt and validate the message. An on-path attacker who captures one legitimate AES-GCM AuthEnvelopedData addressed to the victim can re-emit it with the recipientInfos set left byte-for-byte intact, so the victim's private key still unwraps the genuine CEK (the content-encryption key), but with the inner OID rewritten to AES-256-OFB (Output Feedback Mode, an unauthenticated keystream mode) and with an attacker-chosen IV and ciphertext. The victim initializes AES-256-OFB under the real CEK, never consults the MAC field, and CMS_decrypt() returns success. If the application under attack responds to the attacker with any indicator showing success or failure of the decryption effort, it is possible for the attacker to use this as an oracle to obtain key equivalent functionality for the CEK used for the chosen recipient of the message. In another use case, an attacker can reduce the tag length of the chosen AEAD cipher for a given AuthEnvelopedData container to be a single byte long, allowing an attacker to brute force CMS decryption, producing an integrity bypass for applications that trust CMS_decrypt() to reject modified content. The FIPS modules are not affected by this issue.
References
openssl-security@openssl.orghttps://github.com/openssl/openssl/commit/03c1f4d45fb963aee7d5833390c507cd290182bc
openssl-security@openssl.orghttps://github.com/openssl/openssl/commit/439ed7d2c0962ce964482727264668bf277c333f
openssl-security@openssl.orghttps://github.com/openssl/openssl/commit/7947e6a81eb8776802f159fb6762cb7fcf7e34c7
openssl-security@openssl.orghttps://github.com/openssl/openssl/commit/9fd97f8cfdc2c0be214998de3b2b55c8edf6c7ac
openssl-security@openssl.orghttps://github.com/openssl/openssl/commit/d2ca86bcd43e4f17d899f347101766b6107676e0
openssl-security@openssl.orghttps://openssl-library.org/news/secadv/20260609.txt
Impacted products
Vendor Product Version
To clipboard 

{
  "cveTags": [],
  "descriptions": [
    {
      "lang": "en",
      "value": "Issue Summary: Cryptographic Message Services (CMS) processing fails to perform\nsufficient input validation on the cipher and tag length fields of\nAuthEnvelopedData containers, leading to various potential compromises.\n\nImpact Summary: Attackers making use of these vulnerabilities may achieve\nkey-equivalent functionality for a given CMS recipient and/or bypass integrity\nvalidation for a given message.\n\nIn one use case, an attacker may send a CMS message containing\nAuthEnvelopedData with the cipher specified as a non-AEAD cipher.  OpenSSL\nerroneously allows this selection, and attempts to decrypt and validate the\nmessage.\n\nAn on-path attacker who captures one legitimate AES-GCM AuthEnvelopedData\naddressed to the victim can re-emit it with the recipientInfos set left\nbyte-for-byte intact, so the victim\u0027s private key still unwraps the genuine CEK\n(the content-encryption key), but with the inner OID rewritten to AES-256-OFB\n(Output Feedback Mode, an unauthenticated keystream mode) and with an\nattacker-chosen IV and ciphertext. The victim initializes AES-256-OFB under the\nreal CEK, never consults the MAC field, and CMS_decrypt() returns success.\n\nIf the application under attack responds to the attacker with any indicator\nshowing success or failure of the decryption effort, it is possible for the\nattacker to use this as an oracle to obtain key equivalent functionality for the\nCEK used for the chosen recipient of the message.\n\nIn another use case, an attacker can reduce the tag length of the chosen AEAD\ncipher for a given AuthEnvelopedData container to be a single byte long,\nallowing an attacker to brute force CMS decryption, producing an integrity\nbypass for applications that trust CMS_decrypt() to reject modified content.\n\nThe FIPS modules are not affected by this issue."
    }
  ],
  "id": "CVE-2026-34182",
  "lastModified": "2026-06-10T17:16:32.480",
  "metrics": {
    "cvssMetricV31": [
      {
        "cvssData": {
          "attackComplexity": "LOW",
          "attackVector": "NETWORK",
          "availabilityImpact": "NONE",
          "baseScore": 9.1,
          "baseSeverity": "CRITICAL",
          "confidentialityImpact": "HIGH",
          "integrityImpact": "HIGH",
          "privilegesRequired": "NONE",
          "scope": "UNCHANGED",
          "userInteraction": "NONE",
          "vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N",
          "version": "3.1"
        },
        "exploitabilityScore": 3.9,
        "impactScore": 5.2,
        "source": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
        "type": "Secondary"
      }
    ]
  },
  "published": "2026-06-09T17:17:04.857",
  "references": [
    {
      "source": "openssl-security@openssl.org",
      "url": "https://github.com/openssl/openssl/commit/03c1f4d45fb963aee7d5833390c507cd290182bc"
    },
    {
      "source": "openssl-security@openssl.org",
      "url": "https://github.com/openssl/openssl/commit/439ed7d2c0962ce964482727264668bf277c333f"
    },
    {
      "source": "openssl-security@openssl.org",
      "url": "https://github.com/openssl/openssl/commit/7947e6a81eb8776802f159fb6762cb7fcf7e34c7"
    },
    {
      "source": "openssl-security@openssl.org",
      "url": "https://github.com/openssl/openssl/commit/9fd97f8cfdc2c0be214998de3b2b55c8edf6c7ac"
    },
    {
      "source": "openssl-security@openssl.org",
      "url": "https://github.com/openssl/openssl/commit/d2ca86bcd43e4f17d899f347101766b6107676e0"
    },
    {
      "source": "openssl-security@openssl.org",
      "url": "https://openssl-library.org/news/secadv/20260609.txt"
    }
  ],
  "sourceIdentifier": "openssl-security@openssl.org",
  "vulnStatus": "Awaiting Analysis",
  "weaknesses": [
    {
      "description": [
        {
          "lang": "en",
          "value": "CWE-354"
        }
      ],
      "source": "openssl-security@openssl.org",
      "type": "Secondary"
    }
  ]
}


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