{"cve":"CVE-2021-23017","nvd":{"published":"2021-06-01T13:15:07.853","modified":"2026-06-17T03:38:13.130","status":"Modified","description":"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.","cvss_v4":null,"cvss_v3":{"version":"3.1","vector":"CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:L","score":7.7},"cwes":["CWE-193"],"references":["http://mailman.nginx.org/pipermail/nginx-announce/2021/000300.html","http://packetstormsecurity.com/files/167720/Nginx-1.20.0-Denial-Of-Service.html","https://lists.apache.org/thread.html/r37e6b2165f7c910d8e15fd54f4697857619ad2625f56583802004009%40%3Cnotifications.apisix.apache.org%3E","https://lists.apache.org/thread.html/r4d4966221ca399ce948ef34884652265729d7d9ef8179c78d7f17e7f%40%3Cnotifications.apisix.apache.org%3E","https://lists.apache.org/thread.html/r6fc5c57b38e93e36213e9a18c8a4e5dbd5ced1c7e57f08a1735975ba%40%3Cnotifications.apisix.apache.org%3E"],"products":["f5:nginx","fedoraproject:fedora","netapp:ontap_select_deploy_administration_utility","openresty:openresty","oracle:blockchain_platform","oracle:communications_control_plane_monitor","oracle:communications_fraud_monitor","oracle:communications_operations_monitor","oracle:communications_session_border_controller","oracle:enterprise_communications_broker","oracle:enterprise_session_border_controller","oracle:enterprise_telephony_fraud_monitor","oracle:goldengate"],"source":"nvd","synced_at":"2026-10-19T21:18:09.669877188+00:00"},"epss":{"cve":"CVE-2021-23017","score":0.53461,"percentile":0.98991,"date":"2026-10-31"},"kev":null,"osv":[],"attribution":["This product uses the NVD API but is not endorsed or certified by the NVD.","EPSS scores: FIRST Exploit Prediction Scoring System, https://www.first.org/epss","Known exploited vulnerabilities: CISA Known Exploited Vulnerabilities Catalog, https://www.cisa.gov/known-exploited-vulnerabilities-catalog","Package advisories: OSV (https://osv.dev), from the GitHub Advisory Database, PyPA, Go, RustSec and other ecosystem databases, under CC-BY 4.0 or CC0","CVE records: the CVE Program's CVE List (https://www.cve.org), under its terms of use (https://www.cve.org/Legal/TermsOfUse). CVE is a registered trademark of The MITRE Corporation; this product is not affiliated with the CVE Program."]}