FKIE_CVE-2026-7383

Vulnerability from fkie_nvd - Published: 2026-06-09 17:17 - Updated: 2026-06-10 08:16
Severity
8.1 (High) - CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H
Summary
Issue summary: A signed integer overflow when sizing the destination buffer for Unicode output in ASN1_mbstring_ncopy() can lead to a heap buffer overflow. Impact summary: A heap buffer overflow may lead to a crash or possibly attacker controlled code execution or other undefined behaviour. In ASN1_mbstring_copy() and ASN1_mbstring_ncopy() the destination size for Unicode output is computed in a signed int: by left shift of the input character count for BMPSTRING (UTF-16) and UNIVERSALSTRING (UTF-32), and by summing per-character byte counts for UTF8STRING. The calculation overflows when the input reaches around 2^30 characters. In the worst case (UNIVERSALSTRING at 2^30 characters) the size wraps to zero, OPENSSL_malloc(1) is called, and the subsequent character copy writes several gigabytes past the one-byte allocation. X.509 certificate processing routes through ASN1_STRING_set_by_NID(), whose DIRSTRING_TYPE mask excludes UNIVERSALSTRING and whose per-NID size limits cap the input length; no network protocol or certificate-handling path in OpenSSL exercises the overflow. Triggering the bug requires an application that calls ASN1_mbstring_copy() or ASN1_mbstring_ncopy() directly, or registers a custom string type via ASN1_STRING_TABLE_add(), with attacker-controlled input on the order of half a gigabyte or more. For these reasons this issue was assigned Low severity. The FIPS modules in 4.0, 3.6, 3.5, 3.4 and 3.0 are not affected by this issue, as the affected code is outside the OpenSSL FIPS module boundary.
References
openssl-security@openssl.orghttps://github.com/openssl/openssl/commit/4f8d2bddaa2c8e06f9c33390ee1717059a6e4be6
openssl-security@openssl.orghttps://github.com/openssl/openssl/commit/80c15faaf78042bbb8654a0e234c50c381732f74
openssl-security@openssl.orghttps://github.com/openssl/openssl/commit/bd17511070fb39a67bfa19682affb765e706a974
openssl-security@openssl.orghttps://github.com/openssl/openssl/commit/c332adaced43bcbb85f97410597e951c11ec3083
openssl-security@openssl.orghttps://github.com/openssl/openssl/commit/d32350ae8ef7426718f5aa9e383d4b51398ee255
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: A signed integer overflow when sizing the destination\nbuffer for Unicode output in ASN1_mbstring_ncopy() can lead to a heap\nbuffer overflow.\n\nImpact summary: A heap buffer overflow may lead to a crash or possibly\nattacker controlled code execution or other undefined behaviour.\n\nIn ASN1_mbstring_copy() and ASN1_mbstring_ncopy() the destination\nsize for Unicode output is computed in a signed int: by left shift\nof the input character count for BMPSTRING (UTF-16) and\nUNIVERSALSTRING (UTF-32), and by summing per-character byte counts\nfor UTF8STRING. The calculation overflows when the input reaches\naround 2^30 characters. In the worst case (UNIVERSALSTRING at 2^30\ncharacters) the size wraps to zero, OPENSSL_malloc(1) is called, and\nthe subsequent character copy writes several gigabytes past the\none-byte allocation.\n\nX.509 certificate processing routes through ASN1_STRING_set_by_NID(),\nwhose DIRSTRING_TYPE mask excludes UNIVERSALSTRING and whose per-NID\nsize limits cap the input length; no network protocol or\ncertificate-handling path in OpenSSL exercises the overflow.\nTriggering the bug requires an application that calls\nASN1_mbstring_copy() or ASN1_mbstring_ncopy() directly, or registers\na custom string type via ASN1_STRING_TABLE_add(), with\nattacker-controlled input on the order of half a gigabyte or more.\nFor these reasons this issue was assigned Low severity.\n\nThe FIPS modules in 4.0, 3.6, 3.5, 3.4 and 3.0 are not affected by\nthis issue, as the affected code is outside the OpenSSL FIPS module\nboundary."
    }
  ],
  "id": "CVE-2026-7383",
  "lastModified": "2026-06-10T08:16:25.463",
  "metrics": {
    "cvssMetricV31": [
      {
        "cvssData": {
          "attackComplexity": "HIGH",
          "attackVector": "NETWORK",
          "availabilityImpact": "HIGH",
          "baseScore": 8.1,
          "baseSeverity": "HIGH",
          "confidentialityImpact": "HIGH",
          "integrityImpact": "HIGH",
          "privilegesRequired": "NONE",
          "scope": "UNCHANGED",
          "userInteraction": "NONE",
          "vectorString": "CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H",
          "version": "3.1"
        },
        "exploitabilityScore": 2.2,
        "impactScore": 5.9,
        "source": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
        "type": "Secondary"
      }
    ]
  },
  "published": "2026-06-09T17:17:50.337",
  "references": [
    {
      "source": "openssl-security@openssl.org",
      "url": "https://github.com/openssl/openssl/commit/4f8d2bddaa2c8e06f9c33390ee1717059a6e4be6"
    },
    {
      "source": "openssl-security@openssl.org",
      "url": "https://github.com/openssl/openssl/commit/80c15faaf78042bbb8654a0e234c50c381732f74"
    },
    {
      "source": "openssl-security@openssl.org",
      "url": "https://github.com/openssl/openssl/commit/bd17511070fb39a67bfa19682affb765e706a974"
    },
    {
      "source": "openssl-security@openssl.org",
      "url": "https://github.com/openssl/openssl/commit/c332adaced43bcbb85f97410597e951c11ec3083"
    },
    {
      "source": "openssl-security@openssl.org",
      "url": "https://github.com/openssl/openssl/commit/d32350ae8ef7426718f5aa9e383d4b51398ee255"
    },
    {
      "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-787"
        }
      ],
      "source": "openssl-security@openssl.org",
      "type": "Secondary"
    }
  ]
}


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