{"id":87153,"date":"2026-07-09T09:36:13","date_gmt":"2026-07-09T09:36:13","guid":{"rendered":""},"modified":"-0001-11-30T00:00:00","modified_gmt":"-0001-11-30T00:00:00","slug":"cve-2025-20241-critical-denial-of-service-vulnerability-in-cisco-nx-os-software","status":"publish","type":"post","link":"https:\/\/www.ameeba.com\/blog\/cve-2025-20241-critical-denial-of-service-vulnerability-in-cisco-nx-os-software\/","title":{"rendered":"CVE-2025-20241: Critical Denial of Service Vulnerability in Cisco NX-OS Software<\/strong>"},"content":{"rendered":"

Overview<\/strong><\/p>\n

This report discusses CVE-2025-20241, a critical vulnerability discovered in the Intermediate System-to-Intermediate System (IS-IS) feature of Cisco NX-OS Software. This vulnerability, affecting Cisco Nexus 3000 Series Switches and Cisco Nexus 9000 Series Switches in standalone NX-OS mode, could potentially lead to system compromise or data leakage. Its severity and wide-ranging impact make this vulnerability a significant concern for all organizations using affected Cisco products.<\/p>\n

Vulnerability Summary<\/strong><\/p>\n

CVE ID: CVE-2025-20241
\nSeverity: Critical (CVSS 7.4)
\nAttack Vector: Network
\nPrivileges Required: None
\nUser Interaction: None
\nImpact: Successful exploitation could cause an unexpected restart of the IS-IS process, resulting in a device reload and a potential Denial of Service (DoS) condition.<\/p>\n

Affected Products<\/strong><\/p>\n

Product | Affected Versions<\/p>\n

Cisco NX-OS Software for Cisco Nexus 3000 Series Switches | All affected versions
\nCisco NX-OS Software for Cisco Nexus 9000 Series Switches in standalone NX-OS mode | All affected versions<\/p>\n

How the Exploit Works<\/strong><\/p>\n

The vulnerability is a result of inadequate input validation when parsing an incoming IS-IS packet. An attacker could exploit this vulnerability by sending a specially crafted IS-IS packet to an affected device. Successful exploitation of this vulnerability would cause the IS-IS process to unexpectedly restart, leading to a device reload and potentially causing a Denial of Service (DoS) condition.<\/p>\n

Conceptual Example Code<\/strong><\/p>\n

While the following is not an actual exploit code, it illustrates the general concept of how an attacker might exploit this vulnerability:<\/p>\n

# Attacker sends a crafted IS-IS packet to the vulnerable device\nsend_packet --dest_ip  --protocol IS-IS --payload <\/code><\/pre>\n
Please note that this is a simplified conceptual example, and actual exploitation would require in-depth knowledge of the IS-IS protocol and crafting malicious payloads.<\/p>\n","protected":false},"excerpt":{"rendered":"
Overview This report discusses CVE-2025-20241, a critical vulnerability discovered in the Intermediate System-to-Intermediate System (IS-IS) feature of Cisco NX-OS Software. This vulnerability, affecting Cisco Nexus 3000 Series Switches and Cisco Nexus 9000 Series Switches in standalone NX-OS mode, could potentially lead to system compromise or data leakage. Its severity and wide-ranging impact make this vulnerability […]<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"om_disable_all_campaigns":false,"_monsterinsights_skip_tracking":false,"footnotes":""},"categories":[],"tags":[],"vendor":[],"product":[],"attack_vector":[],"asset_type":[],"severity":[],"exploit_status":[],"class_list":["post-87153","post","type-post","status-publish","format-standard","hentry"],"aioseo_notices":[],"aioseo_head":"\n\t\t\n\t\n\t\n\t\n\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t