Inefficient Regular Expression Complexity in nltk/nltk
Priority LOW 36CWE-1333Published · Updated
Key facts
- Attack vector
- Network
- Privileges required
- None
- User interaction
- None
- Attack complexity
- Low
- Impact type
- Denial of service
- Confidentiality · integrity · availability
- None · None · High
- Fix status
- Fixed
Attack profile from CVSS 3.1 · NVD. Fix status from CNA and GitHub. Impact type from CWE-1333.
Summary
nltk is vulnerable to Inefficient Regular Expression Complexity
Why it matters now
EPSS 0.01571 75th percentileScored 2026-11-07
Public exploit Yes 1 exploit referenceTagged by NVD
Fix Fixed nltk/nltk (nltk): 3.6.6nltk (PyPI): 3.6.6
SSVC decision points
Not available: CISA has not published SSVC decision points for this record.
Affected products
| Vendor | Product | Affected versions | Fixed in | Status | Source |
|---|---|---|---|---|---|
| nltk | nltk/nltk | before 3.6.6 | 3.6.6 | Patch available | CNA |
| — | nltk (PyPI) | before 3.6.6 | 3.6.6 | Patch available | GHSA-rqjh-jp2r-59cj |
- nltk/nltk Vendornltk Affected before 3.6.6 Fixed in 3.6.6 Patch available CNA
- nltk (PyPI) Vendor— Affected before 3.6.6 Fixed in 3.6.6 Patch available GHSA-rqjh-jp2r-59cj
CPE configurations NVD · 5
| CPE | Versions | Role | Vendor |
|---|---|---|---|
| cpe:2.3:a:nltk:nltk:*:*:*:*:*:*:*:* | before 3.6.6 | Vulnerable | nltk |
| cpe:2.3:o:debian:debian_linux:9.0:*:*:*:*:*:*:* | 9.0 | Vulnerable | Debian |
| cpe:2.3:o:debian:debian_linux:10.0:*:*:*:*:*:*:* | 10.0 | Vulnerable | Debian |
| cpe:2.3:o:debian:debian_linux:11.0:*:*:*:*:*:*:* | 11.0 | Vulnerable | Debian |
| cpe:2.3:o:fedoraproject:fedora:35:*:*:*:*:*:*:* | 35 | Vulnerable | Fedoraproject |
- cpe:2.3:a:nltk:nltk:*:*:*:*:*:*:*:* Versions before 3.6.6 Vulnerable ·nltk
- cpe:2.3:o:debian:debian_linux:9.0:*:*:*:*:*:*:* Versions 9.0 Vulnerable ·Debian
- cpe:2.3:o:debian:debian_linux:10.0:*:*:*:*:*:*:* Versions 10.0 Vulnerable ·Debian
- cpe:2.3:o:debian:debian_linux:11.0:*:*:*:*:*:*:* Versions 11.0 Vulnerable ·Debian
- cpe:2.3:o:fedoraproject:fedora:35:*:*:*:*:*:*:* Versions 35 Vulnerable ·Fedoraproject
Remediation
- Fix · CNA nltk/nltk (nltk) Fixed in 3.6.6
- Fix · GHSA-rqjh-jp2r-59cj nltk (PyPI) Fixed in 3.6.6 Advisory →
Vendor assessments
Timeline
- 2026-10-02 Threatist record created from CVE-2021-3842
- 2026-10-03 Alias added: GHSA-rqjh-jp2r-59cj
References
More Nltk vulnerabilities
- TI-2026-00629 Arbitrary Code Execution in NLTK StanfordSegmenter via Untrusted JAR Loading CVSS 3.0CRITICAL 10.0
- TI-2025-12800 Zip Slip Vulnerability in nltk/nltk Leading to Remote Code Execution CVSS 3.0CRITICAL 10.0
- TI-2026-55173 NLTK before 3.10.3 JVM Argument Injection via Per-Call Options CVSS 4.0CRITICAL 9.3
- TI-2026-55155 NLTK before 3.10.3 Remote Code Execution via Unsafe Pickle Deserialization CVSS 4.0CRITICAL 9.3
- TI-2026-56370 nltk PorterStemmer before 3.10.3 Quadratic-time DoS CVSS 4.0HIGH 8.7
- TI-2026-55172 NLTK 3.10.2 Path Traversal via corpus-reader constructors CVSS 4.0HIGH 8.8
Sources
- CVE-2021-3842 · CVE Program
- CVE-2021-3842 · NVD
- FIRST EPSS
- GHSA-rqjh-jp2r-59cj · GitHub Advisory Database · CC BY 4.0
- CVE-2021-3842 · Red Hat security data · CC BY 4.0
This product uses the NVD API but is not endorsed or certified by the NVD. Sources and licences