NLTKGHSA-2ww3-fxvq-293j
NLTK Vulnerable to REDoS
High7.5CVE-2021-3828 · Published Sep 29, 2021 · updated Oct 7, 2024
Affected versions
| Package | Affected | Fixed in |
|---|---|---|
| nltk PyPI | < 3.6.4 | 3.6.4 |
Details and references
The nltk package is vulnerable to ReDoS (regular expression denial of service). An attacker that is able to provide as an input to the [`_read_comparison_block()`(https://github.com/nltk/nltk/blob/23f4b1c4b4006b0cb3ec278e801029557cec4e82/nltk/corpus/reader/comparative_sents.py#L259) function in the file `nltk/corpus/reader/comparative_sents.py` may cause an application to consume an excessive amount of CPU.
- CVSS 3.1
- CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
- Severity from
- GitHub (reviewed advisory)
- Weakness
- CWE-1333, CWE-697
- Also known as
- CVE-2021-3828, PYSEC-2021-356
- nvd.nist.gov/vuln/detail/CVE-2021-3828
- github.com/nltk/nltk/pull/2816
- github.com/nltk/nltk/commit/277711ab1dec729e626b27aab6fa35ea5efbd7e6
- github.com/advisories/GHSA-2ww3-fxvq-293j
- github.com/nltk/nltk
- github.com/pypa/advisory-database/tree/main/vulns/nltk/PYSEC-2021-356.yaml
- huntr.dev/bounties/d19aed43-75bc-4a03-91a0-4d0bb516bc32
More NLTK advisories
All NLTK| Date | Advisory | Severity | Fixed in |
|---|---|---|---|
| Jan 62022 | Inefficient Regular Expression Complexity in nltk (word_tokenize, sent_tokenize) CVE-2021-43854High7.5fixed in 3.6.6 | High7.5 | 3.6.6 |
| Jan 62022 | NLTK Vulnerable to REDoS CVE-2021-3842High7.5fixed in 3.6.6 | High7.5 | 3.6.6 |
| Aug 232019 | NLTK Vulnerable To Path Traversal CVE-2019-14751High7.5fixed in 3.4.5 | High7.5 | 3.4.5 |
| Jun 282024 | ntlk unsafe deserialization vulnerability CVE-2024-39705High7.5fixed in 3.9 | High7.5 | 3.9 |
| Feb 18 | NLTK has a Zip Slip Vulnerability CVE-2025-14009Critical10.0fixed in 3.9.3 | Critical10.0 | 3.9.3 |
| Mar 4 | NLTK has a Path Traversal issue CVE-2026-0847High8.6no fix yet | High8.6 | No fix yet |