{
  "affected": [
    {
      "ranges": [
        {
          "database_specific": {
            "extracted_events": [
              {
                "introduced": "3.13.0"
              },
              {
                "fixed": "3.13.15"
              },
              {
                "introduced": "3.14.0"
              },
              {
                "fixed": "3.14.7"
              },
              {
                "introduced": "3.15.0a1"
              },
              {
                "fixed": "3.15.0rc1"
              }
            ],
            "source": [
              "AFFECTED_FIELD",
              "REFERENCES"
            ]
          },
          "events": [
            {
              "introduced": "60403a5409ff2c3f3b07dd2ca91a7a3e096839c7"
            },
            {
              "introduced": "ebf955df7a89ed0c7968f79faec1de49f61ed7cb"
            },
            {
              "introduced": "f31a89bb901067dd105b00cfa90523cf7ffdbbdd"
            },
            {
              "fixed": "4061bc4c35f7c26f25264666d4ba083b93d2f6f9"
            },
            {
              "fixed": "823f0323ee6ec1402088b73bce1a38473cac36dc"
            },
            {
              "fixed": "37e98da7c19a9e5892ee756d6dee08225422cd49"
            },
            {
              "fixed": "063d4555c94ef412c731527dbf30193327f2ee82"
            },
            {
              "fixed": "476fb09cdb0d73e645849d98c610e7e5697ce7c9"
            },
            {
              "fixed": "89f29c760c02774b099ddd6863268eb13fa3946a"
            },
            {
              "fixed": "b09a67a20c464f8288c9f9a6b9c7082a74560024"
            },
            {
              "fixed": "b30c7fa9edd921a118f286e9f90f560777fa693b"
            },
            {
              "fixed": "fd78b565d7c326f96ae903ab945b47f35d829cf4"
            }
          ],
          "repo": "https://github.com/python/cpython",
          "type": "GIT"
        }
      ]
    }
  ],
  "database_specific": {
    "cna_assigner": "PSF",
    "cwe_ids": [
      "CWE-1176"
    ],
    "osv_generated_from": "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/18xxx/CVE-2026-18503.json",
    "unresolved_ranges": [
      {
        "extracted_events": [
          {
            "fixed": "3.10.21"
          },
          {
            "introduced": "3.11.0"
          },
          {
            "fixed": "3.11.16"
          },
          {
            "introduced": "3.12.0"
          },
          {
            "fixed": "3.12.14"
          }
        ],
        "source": "AFFECTED_FIELD"
      }
    ]
  },
  "details": "Attacker-controlled CSV samples can trigger super-linear \nregular-expression work during dialect sniffing and consume significant \nCPU when applications pass unbounded input to csv.Sniffer.sniff().",
  "id": "CVE-2026-18503",
  "modified": "2026-08-13T03:51:55.913883999Z",
  "published": "2026-08-10T13:45:31.618Z",
  "references": [
    {
      "type": "ADVISORY",
      "url": "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/18xxx/CVE-2026-18503.json"
    },
    {
      "type": "ADVISORY",
      "url": "https://mail.python.org/archives/list/security-announce@python.org/thread/KQ7NBMCPAZJHRROQXJQE4GMXGLD5KHBS/"
    },
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-18503"
    },
    {
      "type": "REPORT",
      "url": "https://github.com/python/cpython/issues/98820"
    },
    {
      "type": "FIX",
      "url": "https://github.com/python/cpython/commit/063d4555c94ef412c731527dbf30193327f2ee82"
    },
    {
      "type": "FIX",
      "url": "https://github.com/python/cpython/commit/476fb09cdb0d73e645849d98c610e7e5697ce7c9"
    },
    {
      "type": "FIX",
      "url": "https://github.com/python/cpython/commit/89f29c760c02774b099ddd6863268eb13fa3946a"
    },
    {
      "type": "FIX",
      "url": "https://github.com/python/cpython/commit/b09a67a20c464f8288c9f9a6b9c7082a74560024"
    },
    {
      "type": "FIX",
      "url": "https://github.com/python/cpython/commit/b30c7fa9edd921a118f286e9f90f560777fa693b"
    },
    {
      "type": "FIX",
      "url": "https://github.com/python/cpython/commit/fd78b565d7c326f96ae903ab945b47f35d829cf4"
    },
    {
      "type": "FIX",
      "url": "https://github.com/python/cpython/pull/153694"
    },
    {
      "type": "PACKAGE",
      "url": "https://github.com/python/cpython"
    }
  ],
  "schema_version": "1.9.0",
  "severity": [
    {
      "score": "CVSS:4.0/AV:L/AC:L/AT:N/PR:L/UI:P/VC:N/VI:N/VA:L/SC:N/SI:N/SA:N",
      "type": "CVSS_V4"
    }
  ],
  "summary": "Super-linear CPU usage for unbounded input to csv.Sniffer.sniff()"
}