What is CVE-2021-3761?

CVE-2021-3761 is a high-severity vulnerability in Cloudflare Octorpki, classified under Out-of-bounds Write. CVSS score: 7.5/10. Published 2021-09-09.

How severe is CVE-2021-3761?

High severity. CVSS v3 base score is 7.5 out of 10.

Buffer overflow in Cloudflare Octorpki

CVE-2021-3761

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.

Vulnerability class: Buffer Overflow

EPSS: 0.012 (65.5th percentile) — read the EPSS interpretation.

CVSS v3 metric

CVSS v3 base score 7.5 (High). Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H.

Affected products

Cloudflare Octorpki — versions unspecified
Debian Debian_linux — versions 11.0

Weakness classification (CWE)

CWE-787 — Out-of-bounds Write

References

cna@cloudflare.com (Patch, Third Party Advisory, x_refsource_MISC)
cna@cloudflare.com (vendor-advisory, Third Party Advisory, x_refsource_DEBIAN)

Frequently asked questions

What is CVE-2021-3761?: CVE-2021-3761 is a high-severity vulnerability in Cloudflare Octorpki, classified under Out-of-bounds Write. CVSS score: 7.5/10. Published 2021-09-09.
How severe is CVE-2021-3761?: High severity. CVSS v3 base score is 7.5 out of 10.