CVE-2020-26256

Name: CVE-2020-26256
Creator: NVD / NIST
Published: 2020-12-08T22:15:17.54+00:00
License: https://creativecommons.org/publicdomain/zero/1.0/

MEDIUMCVSS 6.5/10EPSS 1.53%

Last modified Jun 17, 2026

CVE-2020-26256 is a medium-severity vulnerability rated 6.5/10 on the CVSS scale. Fast-csv is an npm package for parsing and formatting CSVs or any other delimited value file in node. In fast-cvs before version 4.3.6 there is a possible ReDoS vulnerability (Regular Expression Denial of Service) when using ignoreEmpty option when parsing. EPSS estimates a 1.53% chance of exploitation in the next 30 days.

Description

Fast-csv is an npm package for parsing and formatting CSVs or any other delimited value file in node. In fast-cvs before version 4.3.6 there is a possible ReDoS vulnerability (Regular Expression Denial of Service) when using ignoreEmpty option when parsing. This has been patched in `v4.3.6` You will only be affected by this if you use the `ignoreEmpty` parsing option. If you do use this option it is recommended that you upgrade to the latest version `v4.3.6` This vulnerability was found using a CodeQL query which identified `EMPTY_ROW_REGEXP` regular expression as vulnerable.

Metrics

CVSS 3.1

6.5/10

CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H

EPSS Probability

1.53%

71.6th percentile

Probability of exploitation in the next 30 days. Learn more

Weakness Enumeration

Affected Software

Vendor	Product	Versions
C2fo	Fast-Csv	< 4.3.6

References

https://github.com/C2FO/fast-csv/commit/4bbd39f26a8cd7382151ab4f5fb102234b2f829ePatch, Third Party Advisory
https://github.com/C2FO/fast-csv/issues/540Third Party Advisory
https://github.com/C2FO/fast-csv/security/advisories/GHSA-8cv5-p934-3hwpThird Party Advisory
https://lgtm.com/query/8609731774537641779/Exploit, Third Party Advisory
https://www.npmjs.com/package/%40fast-csv/parse
https://www.npmjs.com/package/fast-csvProduct, Third Party Advisory
https://github.com/C2FO/fast-csv/commit/4bbd39f26a8cd7382151ab4f5fb102234b2f829ePatch, Third Party Advisory
https://github.com/C2FO/fast-csv/issues/540Third Party Advisory
https://github.com/C2FO/fast-csv/security/advisories/GHSA-8cv5-p934-3hwpThird Party Advisory
https://lgtm.com/query/8609731774537641779/Exploit, Third Party Advisory
https://www.npmjs.com/package/%40fast-csv/parse
https://www.npmjs.com/package/fast-csvProduct, Third Party Advisory

Timeline

Published: Dec 8, 2020
Last Modified: Jun 17, 2026
Status: Modified

Frequently Asked Questions

What is CVE-2020-26256?

How severe is CVE-2020-26256?

CVE-2020-26256 has a CVSS score of 6.5/10 (MEDIUM severity). The EPSS model estimates a 1.53% probability of exploitation in the next 30 days.

How do I fix CVE-2020-26256?

Check the vendor references and advisories linked above for patched versions and mitigation guidance. You can also run a Strix scan to test if your systems are affected.

Are you affected by CVE-2020-26256?

Run a free Strix scan to check your systems for this vulnerability.

Scan your code now

Source: NVD / NIST