{"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":["BIT-libpython-2026-18503","BIT-python-2026-18503","BIT-python-min-2026-18503","PSF-2026-35"],"modified":"2026-08-20T03:30:54.501086330Z","published":"2026-08-10T13:45:31.618Z","database_specific":{"osv_generated_from":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/18xxx/CVE-2026-18503.json","cna_assigner":"PSF","cwe_ids":["CWE-1176"]},"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":"0"},{"introduced":"deaf509e8fc6e0363bd6f26d52ad42f976ec42f2"},{"introduced":"0fb18b02c8ad56299d6a2910be0bab8ad601ef24"},{"introduced":"60403a5409ff2c3f3b07dd2ca91a7a3e096839c7"},{"introduced":"ebf955df7a89ed0c7968f79faec1de49f61ed7cb"},{"introduced":"f31a89bb901067dd105b00cfa90523cf7ffdbbdd"},{"fixed":"3a19c2f0b3e91ce8f23d0cc64d4c9ee557823f24"},{"fixed":"41388c9cb160d0886d5ca00d2e6c8782608a4549"},{"fixed":"2abcf904b8dac8c999d2b3aac76681abb333798a"},{"fixed":"4061bc4c35f7c26f25264666d4ba083b93d2f6f9"},{"fixed":"823f0323ee6ec1402088b73bce1a38473cac36dc"},{"fixed":"37e98da7c19a9e5892ee756d6dee08225422cd49"},{"fixed":"063d4555c94ef412c731527dbf30193327f2ee82"},{"fixed":"476fb09cdb0d73e645849d98c610e7e5697ce7c9"},{"fixed":"89f29c760c02774b099ddd6863268eb13fa3946a"},{"fixed":"b09a67a20c464f8288c9f9a6b9c7082a74560024"},{"fixed":"b30c7fa9edd921a118f286e9f90f560777fa693b"},{"fixed":"fd78b565d7c326f96ae903ab945b47f35d829cf4"}],"database_specific":{"extracted_events":[{"introduced":"0"},{"fixed":"3.10.21"},{"introduced":"3.11.0"},{"fixed":"3.11.16"},{"introduced":"3.12.0"},{"fixed":"3.12.14"},{"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","v3.12.13","v3.10.20","v3.11.15","v3.13.12","v3.14.3","v3.14.2","v3.13.11","v3.13.10","v3.14.1","v3.13.8","v3.11.14","v3.10.19","v3.12.12","v3.14.0","v3.13.7","v3.13.6","v3.13.5","v3.13.4","v3.11.13","v3.10.18","v3.12.11","v3.13.3","v3.11.12","v3.12.10","v3.10.17","v3.13.2","v3.12.9","v3.13.1","v3.12.8","v3.10.16","v3.11.11","v3.13.0","v3.12.7","v3.11.10","v3.10.15","v3.12.6","v3.12.5","v3.12.4","v3.12.3","v3.11.9","v3.10.14","v3.12.2","v3.11.8","v3.12.1","v3.11.7","v3.11.6","v3.12.0","v3.11.5","v3.10.13","v3.11.4","v3.10.12","v3.10.11","v3.11.3","v3.10.10","v3.11.2","v3.10.9","v3.11.1","v3.11.0rc2","v3.10.8","v3.10.7","v3.11.0rc1","v3.10.6","v3.11.0b5","v3.11.0b4","v3.10.5","v3.11.0b3","v3.11.0b2","v3.11.0b1","v3.11.0a7","v3.10.4","v3.10.3","v3.11.0a6","v3.11.0a5","v3.11.0a4","v3.10.2","v3.11.0a3","v3.10.1","v3.10.0rc2","v3.10.0rc1","v3.10.0b4","v3.10.0b3","v3.10.0b2","v3.10.0b1","v3.10.0a7","v3.10.0a1","v3.9.0a2","v3.7.0a2","v3.6.0b1","v3.6.0a3","v3.5.0b1","v3.5.0a4","v3.5.0a3","v3.5.0a2","v3.5.0a1","v3.4.0b3","v3.4.0b2","v3.4.0b1","v3.4.0a4","v3.4.0a3","v3.4.0a2","v3.4.0a1","v3.3.0rc3","v3.3.0rc2","v3.3.0rc1","v3.3.0b2","v3.3.0b1","v3.3.0a4","v3.3.0a3","v3.3.0a2","v3.2rc3","v3.2rc2","v3.2rc1","v3.2b2","v3.2b1","v3.2a4","v3.2a3","v3.2a2","v3.2a1","v3.1","v3.1rc2","v3.1rc1","v3.1b1","v3.1a2","v3.1a1","v3.0rc3","v3.0rc2","v3.0rc1","v3.0b3","v3.0b2","v3.0b1","v3.0a5","v3.0a4","v3.0a3","v3.0a2","v3.0a1","v2.4","v2.4c1","v2.4b2","v2.4b1","v2.4a3","v2.4a2","v2.4a1","v2.3c2","v2.3c1","v2.2a3","v2.1","v2.1c2","v2.1c1","v2.1b2","v2.1b1","v2.1a2","v2.1a1","v2.0","v2.0c1","v2.0b2","v2.0b1","v1.6a2","v1.6a1","v1.5.2","v1.5.2c1","v1.5.2b2","v1.5.2b1","v1.5.2a2","v1.5.2a1","v1.5.1","v1.5","v1.5b2","v1.5b1","v1.5a4","v1.5a3","v1.5a2","v1.5a1","v1.4","v1.4b3","v1.4b2","v1.4b1","v1.3","v1.3b1","v1.2","v1.2b4","v1.2b3","v1.2b2","v1.2b1","v1.1.1","v1.1","v1.0.2","v1.0.1","v0.9.9","v0.9.8"],"database_specific":{"sour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