CVE-2021-3761

Description

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.

How to fix CVE-2021-3761

To remediate CVE-2021-3761, upgrade the affected package to a fixed version below.

• —upgrade to 1.4.2-1~deb11u1 or later
• —upgrade to 1.4.2-1~deb11u1 or later
• —upgrade to 1.3.0 or later
• —upgrade to 1.3.0 or later

Is CVE-2021-3761 being exploited?

Low — EPSS is 0.4%, meaning exploitation activity has not been observed at scale.

Affected packages (4)

• from 0, < 1.4.2-1~deb11u1
• from 0, < 1.4.2-1~deb11u1
• from 0, < 1.3.0
• from 0, < 1.3.0

CVSS scores

References (9)

• ADVISORYnvd.nist.gov/vuln/detail/CVE-2021-3761
• ADVISORYsecurity-tracker.debian.org/tracker/CVE-2021-3761
• PATCHgithub.com/cloudflare/cfrpki
• WEBgithub.com/cloudflare/cfrpki/commit/a8db4e009ef217484598ba1fd1c595b54e0f6422
• WEB