Vulnerability · Published Sep 9, 2021 · Assigned by cloudflare

CVE-2021-3761OctoRPKI lacks contextual out-of-bounds check when validating RPKI ROA maxLength values

High 7.5

In plain English

A high-severity security flaw in octorpki from Cloudflare. There are no confirmed reports of exploitation so far. The chance it is exploited in the next 30 days is estimated at 1.2% (higher than 69% of all known vulnerabilities). Fixed versions are available - upgrade the affected package.

Severity (CVSS 3.1)7.5High

Exploit odds (30 days)1.2%top 31.3% of all CVEs

Exploited in the wildNo reportsnot in CISA KEV

Attack toolingNoneno public tooling known

Official 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.

Affected packages & fixed versions

Ecosystem	Package	Fixed in	Advisory
Debian:12	cfrpki	1.3.0-1	DEBIAN-CVE-2021-3761
Go	github.com/cloudflare/cfrpki	1.3.0	GHSA-c8xp-8mf3-62h9
Go	github.com/cloudflare/cfrpki	1.3.0	GO-2022-0246
Ubuntu:22.04:LTS	cfrpki	1.4.2-1	UBUNTU-CVE-2021-3761

Affected products (as reported)

Vendor	Product	Versions
Cloudflare	octorpki	unspecified – before 1.3.0

References

https://github.com/cloudflare/cfrpki/security/advisories/GHSA-c8xp-8mf3-62h9 x_refsource_MISC
DSA-5041 vendor-advisory, x_refsource_DEBIAN