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CVE-2025-20241

Cisco Nexus 3000 and 9000 Series Switches IS-IS Protocol <TBD> Denial of Service Vulnerability

High7.4EPSS 0.28%
Published
Updated
Reserved
Assigned by
cisco

Description

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.

Scores

CVSS scores of CVE-2025-20241, by who scored it
Scored byCVSSScoreVector
ciscoCNA (assigner)3.1High7.4CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:C/C:N/I:N/A:H
NVDNVD · Deferred3.1High7.4CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:C/C:N/I:N/A:H
EPSS (exploitation in 30 days)
0.28% · top 80% of all CVEs (7 Nov 2026)
CISA SSVC
Exploitation: none · Automatable: no · Technical impact: partial
Loading the EPSS history…

The list uses the assigner's score when there is one, then CISA's, then NVD's: High 7.4.

Weakness

Affected products

  • Cisco · Cisco NX-OS Software

    • affected 9.2(3)
    • affected 7.0(3)I5(2)
    • affected 6.0(2)A8(7a)
    • affected 7.0(3)I4(5)
    • affected 7.0(3)I4(6)
    • affected 7.0(3)I4(3)
    • affected 9.2(2v)
    • affected 7.0(3)I4(7)
    • affected 7.0(3)I4(1)
    • affected 7.0(3)I4(8)
    • affected 7.0(3)I4(2)
    • affected 6.0(2)A8(11)
    • affected 9.2(1)
    • affected 9.2(2t)
    • affected 9.2(3y)
    • affected 7.0(3)I4(1t)
    • affected 7.0(3)I7(6z)
    • affected 9.3(2)
    • affected 7.0(3)F3(3)
    • affected 7.0(3)I7(3z)
    • affected 7.0(3)IM7(2)
    • affected 6.0(2)A8(11b)
    • affected 7.0(3)I7(5a)
    • affected 7.0(3)I6(1)
    • affected 7.0(3)I5(3b)
    • affected 9.2(4)
    • affected 6.0(2)A8(10)
    • affected 6.0(2)A8(2)
    • affected 7.0(3)IC4(4)
    • affected 7.0(3)F3(3c)
    • affected 7.0(3)F3(1)
    • affected 7.0(3)F3(5)
    • affected 7.0(3)I7(2)
    • affected 7.0(3)I5(3)
    • affected 7.0(3)I7(3)
    • affected 6.0(2)A8(6)
    • affected 7.0(3)I6(2)
    • affected 6.0(2)A8(5)
    • affected 9.3(1)
    • affected 6.0(2)A8(7)
    • and 87 more

What to do

Exploitation: The Cisco Product Security Incident Response Team (PSIRT) is not aware of any public announcements or malicious use of the vulnerability that is described in this advisory.

References (1)

Sources

The same CVE in the primary databases and aggregators, to check against.

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Record last updated .