Cisco NX-OS Software: Binding to an Unrestricted IP Address
CVE-2026-20212 is a critical-severity binding to an unrestricted IP address vulnerability in Cisco NX-OS Software from Cisco, with a CVSS 3.1 base score of 9.8 out of 10. It can be exploited remotely over the network by an unauthenticated attacker, without any action from a user. Affected Cisco NX-OS Software versions: 10.3(1); 10.3(2); 10.3(3), and others listed below. The record does not name a fixed version, so check the vendor advisory. There is no confirmed exploitation so far. EPSS estimates a 0.83% chance of exploitation within 30 days, higher than 58% of scored CVEs.
Critical severity: a successful attack would have severe impact.
What to do
- Check which version of Cisco NX-OS Software you run against the affected versions below, and install the vendor's latest release.
- Until you can update, restrict network access to the affected service so it is not reachable from untrusted networks.
Affected products and versions
| Vendor | Product | Affected versions | Fixed in |
|---|---|---|---|
| Cisco | Cisco NX-OS Software | 10.3(1); 10.3(2); 10.3(3); 10.4(1); 10.3(99w); 10.3(3w); 10.3(99x); 10.3(3o); and 32 more ranges | Not stated |
Version data comes from the organisation that assigned the CVE. Confirm against the vendor advisory before deciding you are unaffected.
How the severity score breaks down
- Attack vector
- NetworkCan be exploited remotely over a network, including the internet.
- Attack complexity
- LowNo special conditions are needed; the attack works reliably.
- Privileges required
- NoneNo account or login is needed.
- User interaction
- NoneNo action by a victim is required.
- Scope
- UnchangedImpact stays within the vulnerable component.
- Confidentiality
- HighAll data handled by the component can be read.
- Integrity
- HighData or code can be modified at will.
- Availability
- HighThe component can be taken down completely.
Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H. Scored by CNA (cisco.com).
Official description
A vulnerability in the Silicon One integration for Cisco Nexus 9000 Series Switches could allow an unauthenticated, remote attacker to execute code with root privileges. This vulnerability exists because TCP ports 43210 and 43211 are accessible in the default Layer 3 (L3) virtual routing and forwarding (VRF). A successful exploit could allow the attacker to connect to an affected device and send crafted input that could be executed as code with root privileges. The exploitation of this vulnerability could also cause the S1HAL process to crash, which could cause the device to reload.
Source: the CVE record as published by its numbering authority, via NVD and CVE.org.
The underlying weakness: Binding to an Unrestricted IP Address
The product assigns the address 0.0.0.0 for a database server, a cloud service/instance, or any computing resource that communicates remotely.
How developers prevent this class of flaw
- Assign IP addresses that are not 0.0.0.0.
- Unwanted connections to the configured server may be denied through a firewall or other packet filtering measures.
More Binding to an Unrestricted IP Address vulnerabilities (CWE-1327)
Timeline
- CVE record published.
- CISA published its SSVC assessment (exploitation: none, automatable: yes, technical impact: total).
- Record last changed materially (score, affected products, status or references).
References
Other references
Other vulnerabilities in Cisco NX-OS Software
- 9.8 Critical severity
- 9.8 Critical severity
- 9.8 Critical severity
- 9.8 Critical severity
- 9.8 Critical severity
- 9.8 Critical severity
Recent Binding to an Unrestricted IP Address vulnerabilities
- 10.0 Critical severity
- 8.0 High severity
- 9.2 Critical severity
- 8.8 High severity
- 9.8 Critical severity
- 9.1 Critical severity
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