CVE-2026-18503

EUVD-2026-55630
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().
ProviderTypeBase ScoreAtk. VectorAtk. ComplexityPriv. RequiredVector
PSFCNA
2.4 LOW
LOCAL
LOW
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
Base Score
CVSS 3.x
EPSS Score
Percentile: Unknown
Early Detection
Affected products identified ahead of NVD analysis through intelligence sources.
VendorProductVersionSource
pythoncpython
𝑥
< 3.13.15
CNA
pythoncpython
3.14.0 ≤
𝑥
< 3.14.7
CNA
Common Weakness Enumeration
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/b30c7fa9edd921a118f286e9f90f560777fa693b
https://github.com/python/cpython/issues/98820
https://github.com/python/cpython/pull/153694
https://mail.python.org/archives/list/security-announce@python.org/thread/KQ7NBMCPAZJHRROQXJQE4GMXGLD5KHBS/