CVE-2026-18503

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().

CVSS 4.0

2.4CVSS:4.0/AV:L/AC:L/AT:N/PR:L/UI:P/VC:N/VI:N/VA:L/SC:N/SI:N/SA:N

EPSS

0.1% chance of exploitation in the next 30 days; higher than 1% of CVEs (scores of 2026-10-25)

CWE

CWE-1176

Published

2026-08-10

Modified

2026-10-23

Record from

the NVD, synced 2026-10-24

References

• https://github.com/python/cpython/commit/063d4555c94ef412c731527dbf30193327f2ee82
• https://github.com/python/cpython/commit/476fb09cdb0d73e645849d98c610e7e5697ce7c9
• https://github.com/python/cpython/commit/89f29c760c02774b099ddd6863268eb13fa3946a
• https://github.com/python/cpython/commit/b09a67a20c464f8288c9f9a6b9c7082a74560024
• https://github.com/python/cpython/commit/b30c7fa9edd921a118f286e9f90f560777fa693b

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