CVE-2026-18503: Super-linear CPU usage for unbounded input to csv.Sniffer.sniff()

Published Aug 10, 2026
·
Updated

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().

Affected Software

1 affected component
Python csv.Sniffer

Event History

Aug 10, 2026
CVE Published
via MITRE·01:45 PM
Data Sourced
via MITRE·01:45 PM
DescriptionWeakness
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Frequently Asked Questions

1

What is the severity of CVE-2026-18503?

CVE-2026-18503 is considered a moderate risk with a CVSS score of 4.9.

2

How do I fix CVE-2026-18503?

To mitigate CVE-2026-18503, validate and limit the size of input passed to csv.Sniffer.sniff() before processing.

3

What software is affected by CVE-2026-18503?

CVE-2026-18503 affects the Python csv.Sniffer module.

4

What is the potential impact of CVE-2026-18503?

CVE-2026-18503 can lead to significant CPU consumption, potentially causing denial of service for applications.

5

When was CVE-2026-18503 published?

CVE-2026-18503 was published on August 10, 2026.

Company

Resources

Contact

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CVE-2026-18503 - Super-linear CPU usage for unbounded input to csv.Sniffer.sniff() - SecAlerts