CVE-2021-37533 Apache Commons Net's FTP client trusts the host from PASV response by default
- Exploited in the wild
- Not known
- Fix
- Available
What is CVE-2021-37533?
CVE-2021-37533 is a medium-severity vulnerability in Debian Debian Linux, published on 3 Dec 2022.
Official description
Prior to Apache Commons Net 3.9.0, Net's FTP client trusts the host from PASV response by default. A malicious server can redirect the Commons Net code to use a different host, but the user has to connect to the malicious server in the first place. This may lead to leakage of information about services running on the private network of the client. The default in version 3.9.0 is now false to ignore such hosts, as cURL does. See https://issues.apache.org/jira/browse/NET-711.
Weakness: CWE-20
Which versions are affected by CVE-2021-37533?
2 open source packages ship an affected version, including commons-net:commons-net. It affects 2 products.
| Package | Affected | Fixed in |
|---|---|---|
commons-net:commons-net Maven | All versions | 3.9.0 |
commons-net:commons-net Maven | All versions | 3.9.0 |
Linux distribution packages (1)
apache-commons-net openSUSE:Tumbleweed | All versions | 3.9.0-1.1 |
Products include Apache Commons Net, Debian Debian Linux.
How do I fix CVE-2021-37533?
Upgrade commons-net:commons-net to 3.9.0 or later.
Is CVE-2021-37533 being exploited?
There is no known exploitation of CVE-2021-37533 in the wild and no public exploit code.
Sources
Also known as CLEANSTART-2026-BN50776, CLEANSTART-2026-ZL12705, DEBIAN-CVE-2021-37533, DLA-3251-1, DSA-5307-1, ECHO-8f21-184c-65cc and 17 more.