CVE-2021-43172 Infinite length chain of RRDP repositories
A malicious CA can cause Routinator to hang indefinitely by creating an infinite chain of RRDP repositories, preventing validation completion.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2021-43172?
CVE-2021-43172 is a high-severity denial of service vulnerability in NLnet Labs Routinator, published on 9 Nov 2021. An attacker can exploit it over the internet without logging in, with no action from the victim.
Official description
NLnet Labs Routinator prior to 0.10.2 happily processes a chain of RRDP repositories of infinite length causing it to never finish a validation run. In RPKI, a CA can choose the RRDP repository it wishes to publish its data in. By continuously generating a new child CA that only consists of another CA using a different RRDP repository, a malicious CA can create a chain of CAs of de-facto infinite length. Routinator prior to version 0.10.2 did not contain a limit on the length of such a chain and will therefore continue to process this chain forever. As a result, the validation run will never finish, 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-2021-43172?
2 open source packages ship an affected version, including routinator. It affects 1 product.
| Package | Affected | Fixed in |
|---|---|---|
routinator crates.io | All versions | 0.10.2 |
routinator crates.io | All versions | 0.10.2 |
Products include Nlnetlabs Routinator.
How do I fix CVE-2021-43172?
Upgrade routinator to 0.10.2 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-2021-43172 being exploited?
There is no known exploitation of CVE-2021-43172 in the wild and no public exploit code.
Other vulnerabilities in NLnet Labs Routinator
- CVE-2023-39916 Possible path traversal when storing RRDP responses
- CVE-2026-49235 Routinator crashes on specifically crafted RRDP XML files
- CVE-2026-49233 Routinator cache path traversal using rogue rsync URIs
- CVE-2026-49234 Routinator crashes on specifically crafted ASN strings in the API
- CVE-2023-39915 Crashes on parsing certain invalid RPKI objects
Sources
Also known as DEBIAN-CVE-2021-43172, GHSA-m3x9-623g-35c4, UBUNTU-CVE-2021-43172.