CVE-2021-3842
published 2022-01-04CVE-2021-3842: nltk is vulnerable to Inefficient Regular Expression Complexity
PriorityP434high7.5CVSS 3.1
AVNACLPRNUINSUCNINAH
EPSS
1.46%
70.7th percentile
nltk is vulnerable to Inefficient Regular Expression Complexity
Affected
15 ranges
| Vendor | Product | Version range | Fixed in |
|---|---|---|---|
| debian | debian_linux | — | — |
| debian | debian_linux | — | — |
| debian | debian_linux | — | — |
| debian | nltk | < nltk 3.6.7-1 (bookworm) | nltk 3.6.7-1 (bookworm) |
| fedoraproject | fedora | — | — |
| nltk | nltk | < 3.6.6 | 3.6.6 |
| nltk | nltk | >= 0 < 3.6.7-1 | 3.6.7-1 |
| nltk | nltk | >= 0 < 3.6.7-1 | 3.6.7-1 |
| nltk | nltk | >= 0 < 3.6.7-1 | 3.6.7-1 |
| nltk | nltk | >= 0 < 3.6.6 | 3.6.6 |
| nltk | nltk | >= 0 < 2.0~b9-0ubuntu4.1~esm4 | 2.0~b9-0ubuntu4.1~esm4 |
| nltk | nltk | >= 0 < 3.1-1ubuntu0.1+esm2 | 3.1-1ubuntu0.1+esm2 |
| nltk | nltk | >= 0 < 3.2.5-1ubuntu0.1+esm2 | 3.2.5-1ubuntu0.1+esm2 |
| nltk | nltk | >= 0 < 3.4.5-2ubuntu0.1~esm2 | 3.4.5-2ubuntu0.1~esm2 |
| nltk | nltk_nltk | >= unspecified < 3.6.6 | 3.6.6 |
CVSS provenance
nvdv3.17.5HIGHCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
nvdv3.07.5HIGHCVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
nvdv2.05.0MEDIUMAV:N/AC:L/Au:N/C:N/I:N/A:P
osv7.5HIGH
vendor_debian7.5HIGH
vendor_ubuntu7.5HIGH
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OSV
nltk vulnerabilities
osv·2025-03-24·CVSS 7.5
CVE-2021-3842 [HIGH] nltk vulnerabilities
nltk vulnerabilities
It was discovered that NLTK contained a regex that is susceptible to
catastrophic backtracking. An attacker could possibly use this issue to
cause a denial of service. (CVE-2021-3842, CVE-2021-43854)
GHSA
NLTK Vulnerable to REDoS
ghsa·2022-01-06
CVE-2021-3842 [HIGH] CWE-1333 NLTK Vulnerable to REDoS
NLTK Vulnerable to REDoS
NLTK is vulnerable to REDoS in some RegexpTaggers used in the functions `get_pos_tagger` and `malt_regex_tagger`.
OSV
NLTK Vulnerable to REDoS
osv·2022-01-06
CVE-2021-3842 [HIGH] NLTK Vulnerable to REDoS
NLTK Vulnerable to REDoS
NLTK is vulnerable to REDoS in some RegexpTaggers used in the functions `get_pos_tagger` and `malt_regex_tagger`.
OSV
CVE-2021-3842: nltk is vulnerable to Inefficient Regular Expression Complexity
osv·2022-01-04·CVSS 7.5
CVE-2021-3842 [HIGH] CVE-2021-3842: nltk is vulnerable to Inefficient Regular Expression Complexity
nltk is vulnerable to Inefficient Regular Expression Complexity
Ubuntu
NLTK vulnerabilities
vendor_ubuntu·2025-03-24·CVSS 7.5
CVE-2021-43854 [HIGH] NLTK vulnerabilities
Title: NLTK vulnerabilities
Summary: Several security issues were fixed in NLTK.
It was discovered that NLTK contained a regex that is susceptible to
catastrophic backtracking. An attacker could possibly use this issue to
cause a denial of service. (CVE-2021-3842, CVE-2021-43854)
Instructions: In general, a standard system update will make all the necessary changes.
Debian
CVE-2021-3842: nltk - nltk is vulnerable to Inefficient Regular Expression Complexity
vendor_debian·2021·CVSS 7.5
CVE-2021-3842 [HIGH] CVE-2021-3842: nltk - nltk is vulnerable to Inefficient Regular Expression Complexity
nltk is vulnerable to Inefficient Regular Expression Complexity
Scope: local
bookworm: resolved (fixed in 3.6.7-1)
bullseye: open
forky: resolved (fixed in 3.6.7-1)
sid: resolved (fixed in 3.6.7-1)
trixie: resolved (fixed in 3.6.7-1)
No detection rules found.
No public exploits indexed.
2022-01-04
Published