{"schema_version":"public-product-v1.1","generated_at":"2026-07-21T11:18:27Z","exposure_verdict":"not_assessed","verdict_reason":"Public evidence does not evaluate exact release, platform, enabled features, configuration, compensating controls, or live exposure.","advisory":{"id":"cisco-sa-nxos-n3_9k-isis-dos-FTCXB4Vb","slug":"cisco-sa-nxos-n3_9k-isis-dos-ftcxb4vb","vendor":"Cisco","title":"Cisco Nexus 3000 and 9000 Series Switches IS-IS Protocol Denial of Service Vulnerability","summary":"A vulnerability in the Intermediate System-to-Intermediate System (IS-IS) protocol of Cisco NX-OS Software for the Cisco Nexus 3000 Series Switches and Cisco Nexus 9000 Series Switches in standalone NX-OS mode could allow an unauthenticated, adjacent attacker to cause the IS-IS process to unexpectedly restart, which could cause an affected device to reload. This vulnerability is due to insufficient input validation when parsing an ingress IS-IS packet. An attacker could exploit this vulnerability by sending a crafted IS-IS packet to an affected device. A successful exploit could allow the attacker to cause a denial of service (DoS) condition due to the unexpected restart of the IS-IS process, which could cause the affected device to reload. Note: The IS-IS protocol is a routing protocol. To exploit this vulnerability, an attacker must be Layer 2 adjacent to the affected device. Cisco has released software updates that address this vulnerability. There are no workarounds that address this vulnerability. This advisory is available at the following link:https://sec.cloudapps.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-nxos-n3_9k-isis-dos-FTCXB4Vb This advisory is part of the August 2023 Cisco FXOS and NX-OS Software Security Advisory Bundled Publication. For a complete list of the advisories and links to them, see Cisco Event Response: August 2023 Semiannual Cisco FXOS and NX-OS Software Security Advisory Bundled Publication.","severity":"High","published_at":"2023-08-23T16:00:00Z","updated_at":"2023-08-23T16:00:00Z","source_url":"https://sec.cloudapps.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-nxos-n3_9k-isis-dos-FTCXB4Vb","csaf_url":"https://sec.cloudapps.cisco.com/security/center/contentjson/CiscoSecurityAdvisory/cisco-sa-nxos-n3_9k-isis-dos-FTCXB4Vb/csaf/cisco-sa-nxos-n3_9k-isis-dos-FTCXB4Vb.json","exposure_verdict":"not_assessed","verdict_reason":"Public evidence does not evaluate exact release, platform, enabled features, configuration, compensating controls, or live exposure."},"freshness":{"last_source_refreshed_at":"2026-07-21T05:16:34Z","latest_source_refresh_at":"2026-07-21T05:16:34Z","oldest_source_refresh_at":"2026-07-21T03:00:03Z","all_sources_fresh":true,"sources":[{"source":"cisco_advisories","label":"Cisco advisories","last_success_at":"2026-07-21T03:00:03Z","stale":false},{"source":"cisco_csaf","label":"Cisco CSAF","last_success_at":"2026-07-21T05:14:24Z","stale":false},{"source":"nvd_cves","label":"NVD CVEs","last_success_at":"2026-07-21T05:16:30Z","stale":false},{"source":"cisa_kev","label":"CISA KEV","last_success_at":"2026-07-21T05:16:31Z","stale":false},{"source":"first_epss","label":"EPSS","last_success_at":"2026-07-21T05:16:34Z","stale":false}]},"summary":{"cve_count":1,"visible_product_count":2,"public_evidence_count":2,"kev_count":0,"highest_epss":0.00291},"cves":[{"id":"CVE-2023-20169","kev":false,"epss":{"score":0.00291,"percentile":0.21163,"score_date":"2026-07-20","updated_at":"2026-07-21T05:16:34Z"}}],"public_evidence":[{"product":{"name":"Cisco Nexus 3000 Series Switches","slug":"cisco-nexus-3000-series-switches","vendor":"Cisco"},"cve":{"id":"CVE-2023-20169"},"evidence_type":"structured_affected","evidence_label":{"scope":"CSAF product evidence","label":"product_status known affected"},"evidence_source":"Cisco CSAF","source":"Cisco CSAF","source_document_fetched_at":"2026-07-20T04:10:21Z","csaf_status":"known_affected","csaf_product_status":"known_affected","csaf_product_status_path":"vulnerabilities[].product_status.known_affected","raw_product_name":"Cisco NX-OS Software 10.3(2) when installed on Cisco Nexus 3000 Series Switches","exposure_verdict":"not_assessed","verdict_reason":"Public evidence does not evaluate exact release, platform, enabled features, configuration, compensating controls, or live exposure.","exposure_verdict_reason":"Public evidence does not evaluate exact release, platform, enabled features, configuration, compensating controls, or live exposure.","kev":false,"epss":{"score":0.00291,"score_date":"2026-07-20","updated_at":"2026-07-21T05:16:34Z"},"published_at":"2023-08-23T16:00:00Z","updated_at":"2023-08-23T16:00:00Z","advisory_updated_at":"2023-08-23T16:00:00Z","source_url":"https://sec.cloudapps.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-nxos-n3_9k-isis-dos-FTCXB4Vb","remediation":{"url":"https://sec.cloudapps.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-nxos-n3_9k-isis-dos-FTCXB4Vb"},"row_display_order":1},{"product":{"name":"Cisco Nexus 9000 Series Switches","slug":"cisco-nexus-9000-series-switches","vendor":"Cisco"},"cve":{"id":"CVE-2023-20169"},"evidence_type":"structured_affected","evidence_label":{"scope":"CSAF product evidence","label":"product_status known affected"},"evidence_source":"Cisco CSAF","source":"Cisco CSAF","source_document_fetched_at":"2026-07-20T04:10:21Z","csaf_status":"known_affected","csaf_product_status":"known_affected","csaf_product_status_path":"vulnerabilities[].product_status.known_affected","raw_product_name":"Cisco NX-OS Software 10.3(2) when installed on Cisco Nexus 9000 Series Switches","exposure_verdict":"not_assessed","verdict_reason":"Public evidence does not evaluate exact release, platform, enabled features, configuration, compensating controls, or live exposure.","exposure_verdict_reason":"Public evidence does not evaluate exact release, platform, enabled features, configuration, compensating controls, or live exposure.","kev":false,"epss":{"score":0.00291,"score_date":"2026-07-20","updated_at":"2026-07-21T05:16:34Z"},"published_at":"2023-08-23T16:00:00Z","updated_at":"2023-08-23T16:00:00Z","advisory_updated_at":"2023-08-23T16:00:00Z","source_url":"https://sec.cloudapps.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-nxos-n3_9k-isis-dos-FTCXB4Vb","remediation":{"url":"https://sec.cloudapps.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-nxos-n3_9k-isis-dos-FTCXB4Vb"},"row_display_order":2}]}