FKIE_CVE-2026-9076

Vulnerability from fkie_nvd - Published: 2026-06-09 17:17 - Updated: 2026-06-10 08:16
Severity
7.5 (High) - CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
Summary
Issue summary: When CMS password-based decryption (RFC 3211 / PWRI key unwrap) processes attacker-supplied CMS data, an attacker-chosen stream-mode KEK cipher can trigger a heap out-of-bounds read in kek_unwrap_key(). Impact summary: A heap buffer over-read may trigger a crash which leads to Denial of Service for an application if the input buffer ends at a memory page boundary and the following page is unmapped. There is no information disclosure as the over-read bytes are not revealed to the attacker. The key unwrapping function performs a check-byte test as specified in the RFC that reads 7 bytes from a heap allocation that is based on the wrapped key length from the message. There is a minimum length check based on the block length of the wrapping cipher. However the cipher is selected from an OID carried in the attacker's PWRI keyEncryptionAlgorithm with no requirement that the cipher be a block cipher. When an attacker selects a stream-mode cipher the guard will be ineffective and the allocated buffer containing the unwrapped key can be too small to fit the check-bytes specified in the RFC and a buffer over-read can happen. Applications calling CMS_decrypt() or CMS_decrypt_set1_password() (equivalently openssl cms -decrypt -pwri_password ...) on untrusted CMS data are vulnerable to this issue. No password knowledge is required: the over-read happens during the unwrap attempt before any authentication succeeds. The over-read is limited to a few bytes and is not written to output, so there is no information disclosure. Triggering a crash requires the allocation to border unmapped memory, which is unlikely with the normal allocator. The FIPS modules are not affected by this issue.
References
openssl-security@openssl.orghttps://github.com/openssl/openssl/commit/05b066366842f930fadd9a6e94df98030af431bb
openssl-security@openssl.orghttps://github.com/openssl/openssl/commit/3d8d5bc1056b2f62da9fede23fedbf47e85187b0
openssl-security@openssl.orghttps://github.com/openssl/openssl/commit/715349a1d7c6db970e6815dafb90915f07307f98
openssl-security@openssl.orghttps://github.com/openssl/openssl/commit/77bf00ab13f6ff5e516535432f0328ed70ec0c26
openssl-security@openssl.orghttps://github.com/openssl/openssl/commit/eecbe330977e8d023aae1ca2d9bdbe983ef3fdc6
openssl-security@openssl.orghttps://openssl-library.org/news/secadv/20260609.txt
Impacted products
Vendor Product Version
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{
  "cveTags": [],
  "descriptions": [
    {
      "lang": "en",
      "value": "Issue summary: When CMS password-based decryption (RFC 3211 / PWRI key unwrap)\nprocesses attacker-supplied CMS data, an attacker-chosen stream-mode KEK\ncipher can trigger a heap out-of-bounds read in kek_unwrap_key().\n\nImpact summary: A heap buffer over-read may trigger a crash which leads to\nDenial of Service for an application if the input buffer ends at a memory\npage boundary and the following page is unmapped. There is no information\ndisclosure as the over-read bytes are not revealed to the attacker.\n\nThe key unwrapping function performs a check-byte test as specified in the\nRFC that reads 7 bytes from a heap allocation that is based on the wrapped\nkey length from the message. There is a minimum length check based on the\nblock length of the wrapping cipher. However the cipher is selected from\nan OID carried in the attacker\u0027s PWRI keyEncryptionAlgorithm with no\nrequirement that the cipher be a block cipher. When an attacker selects\na stream-mode cipher the guard will be ineffective and the allocated buffer\ncontaining the unwrapped key can be too small to fit the check-bytes\nspecified in the RFC and a buffer over-read can happen.\n\nApplications calling CMS_decrypt() or CMS_decrypt_set1_password()\n(equivalently openssl cms -decrypt -pwri_password ...) on untrusted CMS\ndata are vulnerable to this issue. No password knowledge is required: the\nover-read happens during the unwrap attempt before any authentication\nsucceeds.\n\nThe over-read is limited to a few bytes and is not written to output, so\nthere is no information disclosure. Triggering a crash requires the\nallocation to border unmapped memory, which is unlikely with the normal\nallocator.\n\nThe FIPS modules are not affected by this issue."
    }
  ],
  "id": "CVE-2026-9076",
  "lastModified": "2026-06-10T08:16:26.063",
  "metrics": {
    "cvssMetricV31": [
      {
        "cvssData": {
          "attackComplexity": "LOW",
          "attackVector": "NETWORK",
          "availabilityImpact": "HIGH",
          "baseScore": 7.5,
          "baseSeverity": "HIGH",
          "confidentialityImpact": "NONE",
          "integrityImpact": "NONE",
          "privilegesRequired": "NONE",
          "scope": "UNCHANGED",
          "userInteraction": "NONE",
          "vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H",
          "version": "3.1"
        },
        "exploitabilityScore": 3.9,
        "impactScore": 3.6,
        "source": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
        "type": "Secondary"
      }
    ]
  },
  "published": "2026-06-09T17:17:50.997",
  "references": [
    {
      "source": "openssl-security@openssl.org",
      "url": "https://github.com/openssl/openssl/commit/05b066366842f930fadd9a6e94df98030af431bb"
    },
    {
      "source": "openssl-security@openssl.org",
      "url": "https://github.com/openssl/openssl/commit/3d8d5bc1056b2f62da9fede23fedbf47e85187b0"
    },
    {
      "source": "openssl-security@openssl.org",
      "url": "https://github.com/openssl/openssl/commit/715349a1d7c6db970e6815dafb90915f07307f98"
    },
    {
      "source": "openssl-security@openssl.org",
      "url": "https://github.com/openssl/openssl/commit/77bf00ab13f6ff5e516535432f0328ed70ec0c26"
    },
    {
      "source": "openssl-security@openssl.org",
      "url": "https://github.com/openssl/openssl/commit/eecbe330977e8d023aae1ca2d9bdbe983ef3fdc6"
    },
    {
      "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-125"
        }
      ],
      "source": "openssl-security@openssl.org",
      "type": "Secondary"
    }
  ]
}


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