CVE-2021-3842 — Regex Denial of Service in Nltk

CWE-1333 — Regex Denial of Service8 documents6 sources
Severity
7.5HIGHNVD
EPSS
0.4%
top 38.58%
CISA KEV
Not in KEV
Exploit
No known exploits
Affected products
5
Nltk NltkNltkDebian Nltk+2 more
Timeline
PublishedJan 4
Latest updateMar 24

Description

nltk is vulnerable to Inefficient Regular Expression Complexity

CVSS vector

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:HExploitability: 3.9 | Impact: 3.6

Affected Packages6 packages

▶NVDnltk/nltk< 3.6.6
▶PyPInltk/nltk< 3.6.6
▶debiandebian/nltk< nltk 3.6.7-1 (bookworm)
▶CVEListV5nltk/nltk_nltkunspecified — 3.6.6
▶Debiannltk/nltk< 3.6.7-1+2

Also affects: Debian Linux 10.0, 11.0, 9.0, Fedora 35

Patches

Patch: github.com ↗Patch: huntr.dev ↗Patch: github.com ↗

🔴Vulnerability Details

4
OSV
nltk vulnerabilities↗2025-03-24
▶
GHSA
NLTK Vulnerable to REDoS↗2022-01-06
▶
OSV
NLTK Vulnerable to REDoS↗2022-01-06
▶
OSV
CVE-2021-3842: nltk is vulnerable to Inefficient Regular Expression Complexity↗2022-01-04
▶

📋Vendor Advisories

2
Ubuntu
NLTK vulnerabilities↗2025-03-24
▶
Debian
CVE-2021-3842: nltk - nltk is vulnerable to Inefficient Regular Expression Complexity↗2021
▶

📄Research Papers

1
arXiv
Threat Assessment in Machine Learning based Systems↗2022-06-30
▶
CVE-2021-3842 — Regex Denial of Service in Nltk Nltk | cvebase