What is CVE-2023-3036?

CVE-2023-3036 is a high-severity vulnerability in Cloudflare Cfnts, classified under Improper Restriction of Operations within the Bounds of a Memory Buffer. CVSS score: 8.6/10. Published 2023-06-14.

How severe is CVE-2023-3036?

High severity. CVSS v3 base score is 8.6 out of 10.

Buffer overflow in Cloudflare Cfnts

CVE-2023-3036

An unchecked read in NTP server in github.com/cloudflare/cfnts prior to commit 783490b https://github.com/cloudflare/cfnts/commit/783490b913f05e508a492cd7b02e3c4ec2297b71 enabled a remote attacker to trigger a panic by sending an NTSAuthenticator packet with extension length longer than the packet contents.

Vulnerability class: Buffer Overflow

Published 2023-06-14 · last modified 2026-06-17.

CVSS v3 metric

CVSS v3 base score 8.6 (High). Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:N/I:N/A:H.

EPSS exploit prediction

EPSS: 0.022 (82.1th percentile), scored 2026-09-30.

Low probability of exploitation in the next 30 days, but still tracked. 82nd percentile — 82.1% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.

EPSS over last 30 days · oldest: 0.022 · newest: 0.022 · change: 0.000

Affected products

Cloudflare Cfnts — versions 0

Weakness classification (CWE)

References

github.com/cloudflare/cfnts/security/advisories/GHSA-pwx6-gw47-96cp (Patch, Third Party Advisory)

Frequently asked questions

What is CVE-2023-3036?: CVE-2023-3036 is a high-severity vulnerability in Cloudflare Cfnts, classified under Improper Restriction of Operations within the Bounds of a Memory Buffer. CVSS score: 8.6/10. Published 2023-06-14.
How severe is CVE-2023-3036?: High severity. CVSS v3 base score is 8.6 out of 10.