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().

Attack Vector Local

Attack Complexity Low

Privileges Required Low

Attack Requirements None

User Interaction Passive

Vulnerable System Confidentiality Impact None

Vulnerable System Integrity Impact None

Vulnerable System Availability Impact Low

Subsequent System Confidentiality Impact None

Subsequent System Integrity Impact None

Subsequent System Availability Impact None

No CVSS v3.1

No CVSS v3.0

No CVSS v2

This CVE is not in the KEV list.

No EPSS score available.

Exploitation none

Automatable no

Technical Impact partial

Default status is the baseline for the product, each version can override it (e.g. patched versions marked unaffected).

Vendor Product Default status Versions
Python Software Foundation CPython unaffected
Version Status Constraints
0 affected < 3.13.15
3.14.0 affected < 3.14.7
3.15.0a1 affected < 3.15.0rc1

No data.

No data.

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Project Subscriptions

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Advisories

No advisories yet.

Fixes

Solution

No solution given by the vendor.

Workaround

No workaround given by the vendor.

References
Link Providers
https://github.com/python/cpython/commit/063d4555c94ef412c731527dbf30193327f2ee82 cve-icon
https://github.com/python/cpython/commit/476fb09cdb0d73e645849d98c610e7e5697ce7c9 cve-icon
https://github.com/python/cpython/commit/89f29c760c02774b099ddd6863268eb13fa3946a cve-icon
https://github.com/python/cpython/commit/b30c7fa9edd921a118f286e9f90f560777fa693b cve-icon
https://github.com/python/cpython/issues/98820 cve-icon
https://github.com/python/cpython/pull/153694 cve-icon
https://mail.python.org/archives/list/security-announce@python.org/thread/KQ7NBMCPAZJHRROQXJQE4GMXGLD5KHBS/ cve-icon
History

Mon, 10 Aug 2026 19:30:00 +0000

Type Values Removed Values Added
Metrics ssvc

{'options': {'Automatable': 'no', 'Exploitation': 'none', 'Technical Impact': 'partial'}, 'version': '2.0.3'}

Mon, 10 Aug 2026 14:45:00 +0000

Type Values Removed Values Added
References

Mon, 10 Aug 2026 14:15:00 +0000

Type Values Removed Values Added
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().
Title Super-linear CPU usage for unbounded input to csv.Sniffer.sniff()
Weaknesses CWE-1176
References
Metrics cvssV4_0

{'score': 2.4, 'vector': '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'}

Projects

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cve-icon MITRE

Status: PUBLISHED

Assigner: PSF

Published:

Updated: 2026-08-10T17:56:28.336Z

Reserved: 2026-07-31T16:35:42.902Z

Link: CVE-2026-18503

cve-icon Vulnrichment

Updated: 2026-08-10T17:56:23.854Z

cve-icon NVD

No data.

cve-icon Redhat

No data.

cve-icon OpenCVE Enrichment

Updated: 2026-08-10T18:00:03Z

Weaknesses