CVE-2021-3842 Inefficient Regular Expression Complexity in nltk/nltk
Attackers can cause denial of service in the nltk library by submitting input that triggers inefficient regular expression complexity.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2021-3842?
CVE-2021-3842 is a high-severity denial of service vulnerability in Debian Debian Linux, published on 4 Jan 2022. An attacker can exploit it over the internet without logging in, with no action from the victim.
Official description
nltk is vulnerable to Inefficient Regular Expression Complexity
Weakness: CWE-1333
Which versions are affected by CVE-2021-3842?
3 open source packages ship an affected version, including nltk. It affects 3 products.
| Package | Affected | Fixed in |
|---|---|---|
nltk PyPI | All versions | 3.6.6 |
nltk PyPI | All versions | 3.6.6 |
nltk PyPI | All versions | 3.6.6 |
Products include Debian Debian Linux, Fedoraproject Fedora, Nltk Nltk.
How do I fix CVE-2021-3842?
Upgrade nltk to 3.6.6 or later.
Upgrade, then put limits on request size, rate and nesting depth so one client cannot exhaust the service. More about Denial of service.
Is CVE-2021-3842 being exploited?
There is no known exploitation of CVE-2021-3842 in the wild and no public exploit code.
Other vulnerabilities in Debian Debian Linux
Sources
Also known as DEBIAN-CVE-2021-3842, GHSA-rqjh-jp2r-59cj, PYSEC-2022-5, UBUNTU-CVE-2021-3842.