CVE-2021-3448

Related Vulnerabilities: CVE-2021-3448  

No description is available for this CVE.

Description

No description is available for this CVE.

Mitigation

The flaw can be prevented by removing `--server=<address>@<interface>` option or by removing the directive `server=<address>@<interface>`. If dnsmasq is being run through NetworkManager, please be aware that NetworkManager automatically configures dnsmasq to use the `server=<address>@<interface>` directive, thus in this case the only way to prevent the flaw is to remove `dns=dnsmasq` from /etc/NetworkManager/NetworkManager.conf file.

If the `server=<address>@<interface>` must be kept active, the impact of this flaw can be reduced by disabling the dnsmasq cache by adding `--cache-size=0` when calling dnsmasq or by adding a line with `cache-size=0` to the dnsmasq configuration file (/etc/dnsmasq.conf by default). If dnsmasq is being run through NetworkManager, create a new file in /etc/NetworkManager/dnsmasq.d/ and add `cache-size=0` to it.

By disabling the cache, you may experience a performance loss in your environment due to all DNS queries being forwarded to the upstream servers. Please evaluate if the mitigation is appropriate for the system’s environment before applying.

Additional Information

  • Bugzilla 1939368: CVE-2021-3448 dnsmasq: fixed outgoing port used when --server is used with an interface name
  • CWE-358: Improperly Implemented Security Check for Standard
  • FAQ: Frequently asked questions about CVE-2021-3448