CVE-2021-23017: F5 Nginx

High severity, CVSS 7.7. EPSS: 53.5% chance of exploitation in the next 30 days.

A security issue in nginx resolver was identified, which might allow an attacker who is able to forge UDP packets from the DNS server to cause 1-byte memory overwrite, resulting in worker process crash or potential other impact.

Affected products

• F5 Nginx: from 0.6.18, before 1.20.1 (fixed in 1.20.1)
• Fedoraproject Fedora: version 33 only; version 34 only
• Netapp Ontap Select Deploy Administration Utility: affected versions not specified
• Openresty Openresty: before 1.19.3.2 (fixed in 1.19.3.2)
• Oracle Blockchain Platform: before 21.1.2 (fixed in 21.1.2)
• Oracle Communications Control Plane Monitor: version 3.4 only; version 4.2 only; version 4.3 only; version 4.4 only
• Oracle Communications Fraud Monitor: from 3.4, up to and including 4.4
• Oracle Communications Operations Monitor: version 3.4 only; version 4.2 only; version 4.3 only; version 4.4 only
• Oracle Communications Session Border Controller: version 8.4 only; version 9.0 only
• Oracle Enterprise Communications Broker: version 3.3.0 only
• Oracle Enterprise Session Border Controller: version 8.4 only; version 9.0 only
• Oracle Enterprise Telephony Fraud Monitor: version 3.4 only; version 4.2 only; version 4.3 only; version 4.4 only
• Oracle Goldengate: before 21.4.0.0.0 (fixed in 21.4.0.0.0)

Published 2021-06-01. Last modified 2026-06-17.