Cisco NX-OS up to 10.5(2) System-to-Intermediate System compiler optimization removal or modification of security-critical code

Summaryinfo

A vulnerability identified as critical has been detected in Cisco NX-OS. This issue affects some unknown processing of the component System-to-Intermediate System. This manipulation causes compiler optimization removal or modification of security-critical code. The identification of this vulnerability is CVE-2025-20241. The attack needs to be done within the local network. There is no exploit available. You should upgrade the affected component.

Detailsinfo

A vulnerability classified as critical was found in Cisco NX-OS. Affected by this vulnerability is some unknown functionality of the component System-to-Intermediate System. The manipulation with an unknown input leads to a compiler optimization removal or modification of security-critical code vulnerability. The CWE definition for the vulnerability is CWE-733. The developer builds a security-critical protection mechanism into the software, but the compiler optimizes the program such that the mechanism is removed or modified. As an impact it is known to affect availability. The summary by CVE is:

A vulnerability in the Intermediate System-to-Intermediate System (IS-IS) feature of Cisco NX-OS Software for 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 the unexpected restart of the IS-IS process, which could cause the affected device to reload, resulting in a denial of service (DoS) condition. Note: The IS-IS protocol is a routing protocol. To exploit this vulnerability, an attacker must be Layer 2-adjacent to the affected device.

The advisory is shared at sec.cloudapps.cisco.com. This vulnerability is known as CVE-2025-20241 since 10/10/2024. The exploitation appears to be easy. The attack can only be initiated within the local network. The exploitation doesn't need any form of authentication. Neither technical details nor an exploit are publicly available. The price for an exploit might be around USD $0-$5k at the moment (estimation calculated on 08/29/2025).

Upgrading eliminates this vulnerability.

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Productinfo

Type

• Router Operating System

Vendor

• Cisco

Name

• NX-OS

Version

• 6.0(2)A8(1)
• 6.0(2)A8(2)
• 6.0(2)A8(3)
• 6.0(2)A8(4)
• 6.0(2)A8(4a)
• 6.0(2)A8(5)
• 6.0(2)A8(6)
• 6.0(2)A8(7)
• 6.0(2)A8(7a)
• 6.0(2)A8(7b)
• 6.0(2)A8(8)
• 6.0(2)A8(9)
• 6.0(2)A8(10)
• 6.0(2)A8(10a)
• 6.0(2)A8(11)
• 6.0(2)A8(11a)
• 6.0(2)A8(11b)
• 7.0(3)F3(1)
• 7.0(3)F3(2)
• 7.0(3)F3(3)
• 7.0(3)F3(3a)
• 7.0(3)F3(3c)
• 7.0(3)F3(4)
• 7.0(3)F3(5)
• 7.0(3)I4(1)
• 7.0(3)I4(1t)
• 7.0(3)I4(2)
• 7.0(3)I4(3)
• 7.0(3)I4(4)
• 7.0(3)I4(5)
• 7.0(3)I4(6)
• 7.0(3)I4(6t)
• 7.0(3)I4(7)
• 7.0(3)I4(8)
• 7.0(3)I4(8a)
• 7.0(3)I4(8b)
• 7.0(3)I4(8z)
• 7.0(3)I4(9)
• 7.0(3)I5(1)
• 7.0(3)I5(2)
• 7.0(3)I5(3)
• 7.0(3)I5(3a)
• 7.0(3)I5(3b)
• 7.0(3)I6(1)
• 7.0(3)I6(2)
• 7.0(3)I7(1)
• 7.0(3)I7(2)
• 7.0(3)I7(3)
• 7.0(3)I7(3z)
• 7.0(3)I7(4)
• 7.0(3)I7(5)
• 7.0(3)I7(5a)
• 7.0(3)I7(6)
• 7.0(3)I7(6z)
• 7.0(3)I7(7)
• 7.0(3)I7(8)
• 7.0(3)I7(9)
• 7.0(3)I7(9w)
• 7.0(3)I7(10)
• 7.0(3)IA7(1)
• 7.0(3)IA7(2)
• 7.0(3)IC4(4)
• 7.0(3)IM7(2)
• 9.2(1)
• 9.2(2)
• 9.2(2t)
• 9.2(2v)
• 9.2(3)
• 9.2(3y)
• 9.2(4)
• 9.3(1)
• 9.3(1z)
• 9.3(2)
• 9.3(3)
• 9.3(4)
• 9.3(5)
• 9.3(5w)
• 9.3(6)
• 9.3(7)
• 9.3(7a)
• 9.3(7k)
• 9.3(8)
• 9.3(9)
• 9.3(10)
• 9.3(11)
• 9.3(12)
• 9.3(13)
• 9.3(14)
• 10.1(1)
• 10.1(2)
• 10.1(2t)
• 10.2(1)
• 10.2(1q)
• 10.2(2)
• 10.2(2a)
• 10.2(3)
• 10.2(3t)
• 10.2(3v)
• 10.2(4)
• 10.2(5)
• 10.2(6)
• 10.2(7)
• 10.2(8)
• 10.3(1)
• 10.3(2)
• 10.3(3)
• 10.3(3o)
• 10.3(3p)
• 10.3(3q)
• 10.3(3r)
• 10.3(3w)
• 10.3(3x)
• 10.3(4)
• 10.3(4a)
• 10.3(4g)
• 10.3(4h)
• 10.3(5)
• 10.3(6)
• 10.3(99w)
• 10.3(99x)
• 10.4(1)
• 10.4(2)
• 10.4(3)
• 10.4(4)
• 10.4(4g)
• 10.5(1)
• 10.5(2)

License

• commercial

Website

• Vendor: https://www.cisco.com/

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