CVE-2026-18503
Super-linear CPU usage for unbounded input to csv.Sniffer.sniff()
At a glance
- Severity
- LOW 2.4
- EPSS
- EPSS 0.12 % · percentile 2 (2026-10-27)
- State
- PUBLISHED
- Published
- Updated
- Assigner
- PSF
- NVD status
- Awaiting Analysis
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().
Scores
| Version | Score | Vector | Scored by |
|---|---|---|---|
| CVSS 4.0 | LOW 2.4 | 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 | PSF |
| CVSS 4.0 | LOW 2.4 | 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/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X | NVD · cna@python.org (Secondary) |
Weaknesses (CWE)
European references
- ENISA EUVD · EUVD-2026-55630
- GCVE · GCVE-0-2026-18503
CERT-FR advisories
- CERTFR-2026-AVI-1385 — Multiples vulnérabilités dans les produits VMware · cert.ssi.gouv.fr
- CERTFR-2026-AVI-1249 — Multiples vulnérabilités dans les produits VMware · cert.ssi.gouv.fr
- CERTFR-2026-AVI-0994 — Vulnérabilité dans CPython · cert.ssi.gouv.fr
Affected products
| Product | Versions |
|---|---|
| Python Software Foundation · CPython | affected 0 < 3.10.21 ; affected 3.11.0 < 3.11.16 ; affected 3.12.0 < 3.12.14 ; affected 3.13.0 < 3.13.15 ; affected 3.14.0 < 3.14.7 ; affected 3.15.0a1 < 3.15.0rc1 |
References
- https://mail.python.org/archives/list/security-announce@python.org/thread/KQ7NBMCPAZJHRROQXJQE4GMXGLD5KHBS/
- https://github.com/python/cpython/pull/153694
- https://github.com/python/cpython/issues/98820
- 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/commit/b09a67a20c464f8288c9f9a6b9c7082a74560024
- https://github.com/python/cpython/commit/fd78b565d7c326f96ae903ab945b47f35d829cf4
Sources
| Source | Licence |
|---|---|
| CVE List (CVEProject cvelistV5) | CVE Program Terms of Use |
| EPSS (FIRST.org) | FIRST — attribution requested |
| ENISA EUVD | ENISA — reproduction authorised, source acknowledged |
| CERT-FR (ANSSI) | Licence Ouverte / Etalab 2.0 |
| NVD (NIST) via fkie-cad/nvd-json-data-feeds | Public domain — this product uses data from the NVD API but is not endorsed or certified by the NVD |