FKIE_CVE-2026-18503

Vulnerability from fkie_nvd - Published: 2026-08-10 14:17 - Updated: 2026-08-18 15:04
Severity
2.4 (Low) - 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
Summary
Attacker-controlled CSV samples can trigger super-linear regular-expression work during dialect sniffing and consume significant CPU when applications pass unbounded input to csv.Sniffer.sniff().
References
cna@python.orghttps://github.com/python/cpython/commit/063d4555c94ef412c731527dbf30193327f2ee82
cna@python.orghttps://github.com/python/cpython/commit/476fb09cdb0d73e645849d98c610e7e5697ce7c9
cna@python.orghttps://github.com/python/cpython/commit/89f29c760c02774b099ddd6863268eb13fa3946a
cna@python.orghttps://github.com/python/cpython/commit/b09a67a20c464f8288c9f9a6b9c7082a74560024
cna@python.orghttps://github.com/python/cpython/commit/b30c7fa9edd921a118f286e9f90f560777fa693b
cna@python.orghttps://github.com/python/cpython/commit/fd78b565d7c326f96ae903ab945b47f35d829cf4
cna@python.orghttps://github.com/python/cpython/issues/98820
cna@python.orghttps://github.com/python/cpython/pull/153694
cna@python.orghttps://mail.python.org/archives/list/security-announce@python.org/thread/KQ7NBMCPAZJHRROQXJQE4GMXGLD5KHBS/
Impacted products
Vendor Product Version
To clipboard 

{
  "affected": [
    {
      "affectedData": [
        {
          "defaultStatus": "unaffected",
          "modules": [
            "csv"
          ],
          "product": "CPython",
          "repo": "https://github.com/python/cpython",
          "vendor": "Python Software Foundation",
          "versions": [
            {
              "lessThan": "3.10.21",
              "status": "affected",
              "version": "0",
              "versionType": "python"
            },
            {
              "lessThan": "3.11.16",
              "status": "affected",
              "version": "3.11.0",
              "versionType": "python"
            },
            {
              "lessThan": "3.12.14",
              "status": "affected",
              "version": "3.12.0",
              "versionType": "python"
            },
            {
              "lessThan": "3.13.15",
              "status": "affected",
              "version": "3.13.0",
              "versionType": "python"
            },
            {
              "lessThan": "3.14.7",
              "status": "affected",
              "version": "3.14.0",
              "versionType": "python"
            },
            {
              "lessThan": "3.15.0rc1",
              "status": "affected",
              "version": "3.15.0a1",
              "versionType": "python"
            }
          ]
        }
      ],
      "source": "cna@python.org"
    }
  ],
  "cveTags": [],
  "descriptions": [
    {
      "lang": "en",
      "value": "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",
  "lastModified": "2026-08-18T15:04:46.610",
  "metrics": {
    "cvssMetricV40": [
      {
        "cvssData": {
          "Automatable": "NOT_DEFINED",
          "Recovery": "NOT_DEFINED",
          "Safety": "NOT_DEFINED",
          "attackComplexity": "LOW",
          "attackRequirements": "NONE",
          "attackVector": "LOCAL",
          "availabilityRequirement": "NOT_DEFINED",
          "baseScore": 2.4,
          "baseSeverity": "LOW",
          "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": "LOW",
          "providerUrgency": "NOT_DEFINED",
          "subAvailabilityImpact": "NONE",
          "subConfidentialityImpact": "NONE",
          "subIntegrityImpact": "NONE",
          "userInteraction": "PASSIVE",
          "valueDensity": "NOT_DEFINED",
          "vectorString": "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/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": "LOW",
          "vulnConfidentialityImpact": "NONE",
          "vulnIntegrityImpact": "NONE",
          "vulnerabilityResponseEffort": "NOT_DEFINED"
        },
        "source": "cna@python.org",
        "type": "Secondary"
      }
    ],
    "ssvcV203": [
      {
        "source": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
        "ssvcData": {
          "id": "CVE-2026-18503",
          "options": [
            {
              "exploitation": "none"
            },
            {
              "automatable": "no"
            },
            {
              "technicalImpact": "partial"
            }
          ],
          "role": "CISA Coordinator",
          "timestamp": "2026-08-10T17:56:17.853221Z",
          "version": "2.0.3"
        }
      }
    ]
  },
  "published": "2026-08-10T14:17:21.560",
  "references": [
    {
      "source": "cna@python.org",
      "url": "https://github.com/python/cpython/commit/063d4555c94ef412c731527dbf30193327f2ee82"
    },
    {
      "source": "cna@python.org",
      "url": "https://github.com/python/cpython/commit/476fb09cdb0d73e645849d98c610e7e5697ce7c9"
    },
    {
      "source": "cna@python.org",
      "url": "https://github.com/python/cpython/commit/89f29c760c02774b099ddd6863268eb13fa3946a"
    },
    {
      "source": "cna@python.org",
      "url": "https://github.com/python/cpython/commit/b09a67a20c464f8288c9f9a6b9c7082a74560024"
    },
    {
      "source": "cna@python.org",
      "url": "https://github.com/python/cpython/commit/b30c7fa9edd921a118f286e9f90f560777fa693b"
    },
    {
      "source": "cna@python.org",
      "url": "https://github.com/python/cpython/commit/fd78b565d7c326f96ae903ab945b47f35d829cf4"
    },
    {
      "source": "cna@python.org",
      "url": "https://github.com/python/cpython/issues/98820"
    },
    {
      "source": "cna@python.org",
      "url": "https://github.com/python/cpython/pull/153694"
    },
    {
      "source": "cna@python.org",
      "url": "https://mail.python.org/archives/list/security-announce@python.org/thread/KQ7NBMCPAZJHRROQXJQE4GMXGLD5KHBS/"
    }
  ],
  "sourceIdentifier": "cna@python.org",
  "vulnStatus": "Awaiting Analysis",
  "weaknesses": [
    {
      "description": [
        {
          "lang": "en",
          "value": "CWE-1176"
        }
      ],
      "source": "cna@python.org",
      "type": "Secondary"
    }
  ]
}



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