CVE-2021-43173 Hanging RRDP request
An attacker can stall RPKI validation by slowly drip-feeding data, causing Routinator to serve stale data or fail to start.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2021-43173?
CVE-2021-43173 is a high-severity denial of service vulnerability in Debian Debian Linux, published on 9 Nov 2021. An attacker can exploit it over the internet without logging in, with no action from the victim.
Official description
In NLnet Labs Routinator prior to 0.10.2, a validation run can be delayed significantly by an RRDP repository by not answering but slowly drip-feeding bytes to keep the connection alive. This can be used to effectively stall validation. While Routinator has a configurable time-out value for RRDP connections, this time-out was only applied to individual read or write operations rather than the complete request. Thus, if an RRDP repository sends a little bit of data before that time-out expired, it can continuously extend the time it takes for the request to finish. Since validation will only continue once the update of an RRDP repository has concluded, this delay will cause validation to stall, leading to Routinator continuing to serve the old data set or, if in the initial validation run directly after starting, never serve any data at all.
Which versions are affected by CVE-2021-43173?
It affects 2 products.
Products include Debian Debian Linux, Nlnetlabs Routinator.
How do I fix CVE-2021-43173?
Upgrade to a fixed version.
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-2021-43173 being exploited?
There is no known exploitation of CVE-2021-43173 in the wild and no public exploit code.
Other vulnerabilities in Debian Debian Linux
Sources
Also known as DEBIAN-CVE-2021-43173, GHSA-pgwq-8wjv-xhhr, UBUNTU-CVE-2021-43173.