TI-2021-01250 Aliases CVE-2021-1523 GHSA-f58x-5qwh-88r6

Cisco Nexus 9000 Series Fabric Switches ACI Mode Queue Wedge Denial of Service Vulnerability

MEDIUM 46CWE-772Published 2021-08-25 · Updated 2024-11-07

Key facts

Attack vector: Network
Privileges required: None
User interaction: None
Attack complexity: Low
Impact type: Denial of service
Confidentiality · integrity · availability: None · None · High
Fix status: No fix listed

Attack profile from CVSS 3.1 · CNA. Fix status from CNA. Impact type from CWE-772.

Summary

A vulnerability in Cisco Nexus 9000 Series Fabric Switches in Application Centric Infrastructure (ACI) Mode could allow an unauthenticated, remote attacker to cause a queue wedge on a leaf switch, which could result in critical control plane traffic to the device being dropped. This could result in one or more leaf switches being removed from the fabric. This vulnerability is due to mishandling of ingress TCP traffic to a specific port. An attacker could exploit this vulnerability by sending a stream of TCP packets to a specific port on a Switched Virtual Interface (SVI) configured on the device. A successful exploit could allow the attacker to cause a specific packet queue to queue network buffers but never process them, leading to an eventual queue wedge. This could cause control plane traffic to be dropped, resulting in a denial of service (DoS) condition where the leaf switches are unavailable. Note: This vulnerability requires a manual intervention to power-cycle the device to recover.

Why it matters now

Exploitation None reported CISA SSVC · not in CISA KEV

EPSS 0.01328 71st percentileScored 2026-11-07

Fix No fix listed No fixed version in the sources yet

SSVC decision points

CISA ADP · SSVC 2.0.3

Exploitation: None
Automatable: Yes
Technical impact: Partial

The decision (Track, Attend, Act) also depends on your mission and well-being impact; see CISA's SSVC guide.

Affected products

Vendor	Product	Affected versions	Fixed in	Status	Source
Cisco	Cisco NX-OS System Software in ACI Mode	all versions	—	No fix listed	CNA

Cisco NX-OS System Software in ACI Mode VendorCisco Affected all versions Fixed in — No fix listed CNA

CPE configurations NVD · 11

CPE	Versions	Role	Vendor
cpe:2.3:o:cisco:nx-os:13.2\(3n\):::::::*	13.2(3n)	Vulnerable	Cisco
cpe:2.3:o:cisco:nx-os:14.2\(4i\):::::::*	14.2(4i)	Vulnerable	Cisco
cpe:2.3:h:cisco:nexus_93120tx:-:::::::*	not specified by NVD	Running on	Cisco
cpe:2.3:h:cisco:nexus_93128tx:-:::::::*	not specified by NVD	Running on	Cisco
cpe:2.3:h:cisco:nexus_9332pq:-:::::::*	not specified by NVD	Running on	Cisco
cpe:2.3:h:cisco:nexus_9372px:-:::::::*	not specified by NVD	Running on	Cisco
cpe:2.3:h:cisco:nexus_9372px-e:-:::::::*	not specified by NVD	Running on	Cisco
cpe:2.3:h:cisco:nexus_9372tx:-:::::::*	not specified by NVD	Running on	Cisco
cpe:2.3:h:cisco:nexus_9372tx-e:-:::::::*	not specified by NVD	Running on	Cisco
cpe:2.3:h:cisco:nexus_9396px:-:::::::*	not specified by NVD	Running on	Cisco

cpe:2.3:o:cisco:nx-os:13.2\(3n\):*:*:*:*:*:*:* Versions 13.2(3n) Vulnerable ·Cisco
cpe:2.3:o:cisco:nx-os:14.2\(4i\):*:*:*:*:*:*:* Versions 14.2(4i) Vulnerable ·Cisco
cpe:2.3:h:cisco:nexus_93120tx:-:*:*:*:*:*:*:* Versions not specified by NVD Running on ·Cisco
cpe:2.3:h:cisco:nexus_93128tx:-:*:*:*:*:*:*:* Versions not specified by NVD Running on ·Cisco
cpe:2.3:h:cisco:nexus_9332pq:-:*:*:*:*:*:*:* Versions not specified by NVD Running on ·Cisco
cpe:2.3:h:cisco:nexus_9372px:-:*:*:*:*:*:*:* Versions not specified by NVD Running on ·Cisco
cpe:2.3:h:cisco:nexus_9372px-e:-:*:*:*:*:*:*:* Versions not specified by NVD Running on ·Cisco
cpe:2.3:h:cisco:nexus_9372tx:-:*:*:*:*:*:*:* Versions not specified by NVD Running on ·Cisco
cpe:2.3:h:cisco:nexus_9372tx-e:-:*:*:*:*:*:*:* Versions not specified by NVD Running on ·Cisco
cpe:2.3:h:cisco:nexus_9396px:-:*:*:*:*:*:*:* Versions not specified by NVD Running on ·Cisco

Show 1 more CPE

CPE	Versions	Role	Vendor
cpe:2.3:h:cisco:nexus_9396tx:-:::::::*	not specified by NVD	Running on	Cisco

cpe:2.3:h:cisco:nexus_9396tx:-:*:*:*:*:*:*:* Versions not specified by NVD Running on ·Cisco

Remediation

No fixed version listed by the sources yet.

Timeline

2026-10-02 Threatist record created from CVE-2021-1523
2026-10-03 Alias added: GHSA-f58x-5qwh-88r6

References

Advisory 1

20210825 Cisco Nexus 9000 Series Fabric Switches ACI Mode Queue Wedge Denial of Service Vulnerability

TI-2023-23979 The HTTP/2 protocol allows a denial of service (server resource consumption) because… KEVCVSS 3.1HIGH 7.5
TI-2024-13332 Cisco NX-OS Software CLI Command Injection Vulnerability KEVCVSS 3.1MEDIUM 6.7
TI-2018-00260 Improper input validation in Cisco NX-OS unknown CVSS 3.0CRITICAL 9.8
TI-2019-01226 Cisco NX-OS Software Netstack Denial of Service Vulnerability CVSS 3.1HIGH 8.6
TI-2022-05183 Cisco NX-OS Software Cisco Fabric Services Over IP Denial of Service Vulnerability CVSS 3.1HIGH 8.6
TI-2022-05182 Cisco Nexus 9000 Series Switches Bidirectional Forwarding Detection Denial of Service Vulnerability CVSS 3.1HIGH 8.6

See all 274 →

Sources

This product uses the NVD API but is not endorsed or certified by the NVD. Sources and licences