CVE-2021-3761: OctoRPKI lacks contextual out-of-bounds check when validating RPKI ROA maxLength values
Any CA issuer in the RPKI can trick OctoRPKI prior to 1.3.0 into emitting an invalid VRP "MaxLength" value, causing RTR sessions to terminate. An attacker can use this to disable RPKI Origin Validation in a victim network (for example AS 13335 - Cloudflare) prior to launching a BGP hijack which during normal operations would be rejected as "RPKI invalid". Additionally, in certain deployments RTR session flapping in and of itself also could cause BGP routing churn, causing availability issues.
Affected Software
Remediation
Recommended actions to resolve this vulnerability, in priority order.
- Upgrade
Upgrade
debian/cfrpkito a version that resolves this vulnerability.Fixed in 1.4.2-1~deb11u1Fixed in 1.4.4-1Fixed in 1.5.10-2 - Upgrade
Upgrade
OctoRPKIto a version that resolves this vulnerability.Fixed in 1.3.0
Event History
Frequently Asked Questions
What is CVE-2021-3761?
CVE-2021-3761 is a vulnerability in OctoRPKI prior to version 1.3.0 that allows any CA issuer in the RPKI to trick OctoRPKI into emitting an invalid VRP "MaxLength" value, causing RTR sessions to terminate.
How does CVE-2021-3761 affect the victim network?
CVE-2021-3761 can be used to disable RPKI Origin Validation in a victim network (for example AS 13335 - Cloudflare) prior to launching a BGP hijack.
What is the severity of CVE-2021-3761?
CVE-2021-3761 has a severity rating of high, with a CVSS score of 7.5.
How can I fix CVE-2021-3761?
To fix CVE-2021-3761, update OctoRPKI to version 1.3.0 or later.
Where can I find more information about CVE-2021-3761?
You can find more information about CVE-2021-3761 at the following references: [1] [2] [3]