{"id":"CVE-2026-18503","summary":"Super-linear CPU usage for unbounded input to csv.Sniffer.sniff()","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().","aliases":["PSF-2026-35"],"modified":"2026-08-13T04:02:14.760839926Z","published":"2026-08-10T13:45:31.618Z","database_specific":{"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"}],"cna_assigner":"PSF","cwe_ids":["CWE-1176"],"osv_generated_from":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/18xxx/CVE-2026-18503.json"},"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"}],"affected":[{"ranges":[{"type":"GIT","repo":"https://github.com/python/cpython","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"}],"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"]}}],"versions":["v3.15.0b4","v3.15.0b3","v3.13.14","v3.14.6","v3.15.0b2","v3.14.5","v3.15.0b1","v3.14.5rc1","v3.13.13","v3.14.4","v3.13.12","v3.14.3","v3.14.2","v3.13.11","v3.13.10","v3.14.1","v3.13.8","v3.14.0","v3.13.7","v3.13.6","v3.13.5","v3.13.4","v3.13.3","v3.13.2","v3.13.1","v3.13.0"],"database_specific":{"source":"https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-18503.json"}}],"schema_version":"1.9.0","severity":[{"type":"CVSS_V4","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"}]}