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().
Does this matter?
Lower severity and a low EPSS score (0.12%). Track it; it rarely justifies an emergency change on its own.
Description
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
- 2.4 LOWCVSS: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/M
- EPSS
- 0.12% probability · 2th percentile
- Public exploits
- None in Exploit-DB
- CISA KEV
- Not listed
- Weakness
- CWE-1176
- Source
- cna@python.org
EPSS 0.1% since 26 October 2026; no change recorded yet. Points are recorded when the score first appears and whenever it moves by a percentage point or more.
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
- https://github.com/python/cpython/commit/fd78b565d7c326f96ae903ab945b47f35d829cf4
- 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/
Source: NVD record, EPSS from FIRST.org, KEV from CISA, exploits from Exploit-DB. Refreshed daily. Download this record as JSON.