CVE-2021-3828

Name: CVE-2021-3828
Creator: NVD / NIST
Published: 2021-09-27T13:15:07.993+00:00
License: https://creativecommons.org/publicdomain/zero/1.0/

HIGHCVSS 7.5/10EPSS 1.58%

Last modified Jun 17, 2026

CVE-2021-3828 is a high-severity vulnerability rated 7.5/10 on the CVSS scale. nltk is vulnerable to Inefficient Regular Expression Complexity. EPSS estimates a 1.58% chance of exploitation in the next 30 days.

Description

nltk is vulnerable to Inefficient Regular Expression Complexity

Metrics

CVSS 3.1

7.5/10

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

EPSS Probability

1.58%

72.5th percentile

Probability of exploitation in the next 30 days. Learn more

Weakness Enumeration

Affected Software

Vendor	Product	Versions
Nltk	Nltk	<= 3.6.3

References

https://github.com/nltk/nltk/commit/277711ab1dec729e626b27aab6fa35ea5efbd7e6Patch, Third Party Advisory
https://huntr.dev/bounties/d19aed43-75bc-4a03-91a0-4d0bb516bc32Exploit, Patch, Third Party Advisory
https://github.com/nltk/nltk/commit/277711ab1dec729e626b27aab6fa35ea5efbd7e6Patch, Third Party Advisory
https://huntr.dev/bounties/d19aed43-75bc-4a03-91a0-4d0bb516bc32Exploit, Patch, Third Party Advisory

Timeline

Published: Sep 27, 2021
Last Modified: Jun 17, 2026
Status: Modified

Frequently Asked Questions

What is CVE-2021-3828?

nltk is vulnerable to Inefficient Regular Expression Complexity

How severe is CVE-2021-3828?

CVE-2021-3828 has a CVSS score of 7.5/10 (HIGH severity). The EPSS model estimates a 1.58% probability of exploitation in the next 30 days.

How do I fix CVE-2021-3828?

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-2021-3828?

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

Scan your code now

Source: NVD / NIST