- Cisco released advisories for five critical vulnerabilities in its NX-OS data center network operating system.
- Cisco said the hardening vulnerabilities were not known to be actively exploited.
- Cisco assigned a base CVSS score of 9.8 to the hardening-release vulnerabilities.
Cisco published security advisories on Oct 7 for five critical vulnerabilities in its NX-OS data center network operating system, the company said. Cisco’s hardening advisory was first published at 16:00 GMT.
The vulnerabilities affect listed Cisco products running a vulnerable NX-OS release, regardless of device configuration. Cisco said they could be exploited to run arbitrary code with root privileges on Nexus switches.
The release followed an internal security review that produced software hardening releases for multiple vulnerabilities. Cisco said the issues were found through existing testing processes and frontier AI models, and were not known to be actively exploited.
On this page
Cisco grouped the hardening issues by vulnerability class
Cisco grouped the issues by their underlying vulnerability class and assigned a single CVE identifier to each class. The hardening release covers MDS 9000 Series Multilayer Switches, Nexus 3000 Series Switches, Nexus 7000 Series Switches and Nexus 9000 Series Fabric Switches in ACI mode.
Cisco assigned a base CVSS score of 9.8 to the hardening-release vulnerabilities. It said the affected products are vulnerable when running a vulnerable NX-OS release, regardless of device configuration.
The NX-OS Python flaw could reach the underlying operating system
A separate NX-OS Python sandbox escape vulnerability could allow an authenticated, local attacker with low privileges to gain unauthorized access to the underlying operating system of an affected device.
A successful exploit could allow the attacker to execute arbitrary commands on the underlying operating system with the privileges of the authenticated user. Cisco assigned this vulnerability a base CVSS score of 4.4.
Cisco said it was not aware of public announcements or malicious use of the Python sandbox escape vulnerability.
HKCERT said some flaws could enable remote code execution
HKCERT said some of the Cisco vulnerabilities could cause denial of service, bypass security restrictions, disclose sensitive information or enable remote code execution on a targeted system.
Cisco has released software updates for the hardening vulnerabilities and said there are no workarounds that address them.
HKCERT published its bulletin on Oct 7 and instructed users to apply fixes issued by Cisco. Cisco said its security review process found the vulnerabilities through internal testing.
What to do now
- Upgrade to the fixed software indicated in Cisco’s hardening advisory.
- Apply fixes issued by the vendor.
FAQ
What did Cisco disclose in the NX-OS advisories?
Cisco released security advisories for five critical vulnerabilities in its NX-OS data center network operating system. The company said the hardening vulnerabilities were found during internal testing and were not known to be actively exploited.
Which Cisco products are affected by the NX-OS flaws?
The hardening release covers MDS 9000, Nexus 3000, Nexus 7000 and Nexus 9000 (ACI mode) products when they run a vulnerable NX-OS release.
Can the Cisco NX-OS flaws enable remote code execution?
Cisco said the vulnerabilities could be exploited to run arbitrary code with root privileges on Nexus switches. HKCERT said some vulnerabilities could enable remote code execution on the targeted system.
Was the NX-OS Python sandbox escape exploited?
Cisco said the Python vulnerability was not known to have been maliciously used and that it was not aware of public announcements about it.
What can the NX-OS Python sandbox escape do?
An authenticated, local, low-privileged attacker could escape the Python sandbox, gain unauthorized access to the underlying operating system and execute arbitrary commands with the authenticated user’s privileges.
How do I fix the Cisco NX-OS vulnerabilities?
Cisco released software updates and strongly recommends upgrading to the fixed software indicated in its hardening advisory. It said there are no workarounds for the hardening vulnerabilities.
Sources
- Cisco warns of critical flaws allowing Nexus switch takeover, HKCERTPrimary
- Cisco Products Multiple Vulnerabilities, HKCERTPrimary
- Cisco NX-OS Software Security Hardening Release: October 2026, CiscoPrimary
- Cisco NX-OS Software Python Sandbox Escape Vulnerability, CiscoPrimary
- Cisco warns of critical flaws allowing Nexus switch takeover, BleepingComputer
- Cisco bundles fixes for multiple vulnerabilities, some critical, into one patch, Network World
How we checked this story
| Claim | Source | Status |
|---|---|---|
| Cisco released security advisories for five critical vulnerabilities in its NX-OS data center network operating system. | Cisco, via HKCERT | Attributed |
| Cisco said the vulnerabilities could be exploited to run arbitrary code with root privileges on Nexus switches. | Cisco, via BleepingComputer | Attributed |
| Cisco's internal security review resulted in software hardening releases addressing multiple internally discovered vulnerabilities. | Cisco | Confirmed |
| The hardening-release vulnerabilities affect listed Cisco products running a vulnerable NX-OS release regardless of device configuration. | Cisco | Confirmed |
| Cisco assigned a base CVSS score of 9.8 to the hardening-release vulnerabilities. | Cisco | Confirmed |
| Cisco said the hardening-release vulnerabilities were found during internal testing and were not known to be actively exploited. | Cisco | Confirmed |
| Cisco assigned a base CVSS score of 4.4 to the NX-OS Python sandbox escape vulnerability. | Cisco | Confirmed |
| Cisco said it was not aware of public announcements or malicious use of the Python sandbox escape vulnerability. | Cisco | Confirmed |
| The Python sandbox escape vulnerability could let an authenticated, local, low-privileged attacker gain unauthorized access to the underlying operating system. | Cisco | Confirmed |
| A successful exploit of the Python vulnerability could let an attacker execute arbitrary operating-system commands with the authenticated user's privileges. | Cisco | Confirmed |
| The Python vulnerability affects listed MDS and Nexus products when a low-privileged user has Python execution privileges. | Cisco | Confirmed |
| Cisco said it released software updates for the hardening vulnerabilities. | Cisco | Confirmed |
| Cisco said there are no workarounds addressing the hardening vulnerabilities. | Cisco | Confirmed |
| Cisco's hardening advisory was first published on 7 October 2026 at 16:00 GMT. | Cisco | Confirmed |
| Cisco said the hardening vulnerabilities were found during internal security testing using existing processes and frontier AI models. | Cisco | Confirmed |
| The HKCERT bulletin said some Cisco vulnerabilities could cause denial of service, bypass security restrictions, disclose sensitive information, or enable remote code execution. | HKCERT | Confirmed |
| HKCERT published its report on Oct 7, 2026. | HKCERT | Confirmed |
| sec.cloudapps.cisco.com published its report on Oct 7, 2026. | sec.cloudapps.cisco.com | Confirmed |
| sec.cloudapps.cisco.com published its report on Oct 7, 2026. | sec.cloudapps.cisco.com | Confirmed |
Could not verify
- How many devices or customers are affected is not established.
- Whether the NX-OS vulnerabilities have been exploited is not established beyond Cisco’s statement that it is not aware of malicious use.
- Whether the five critical vulnerabilities in S1 correspond exactly to the six CVE identifiers in S6 is not established.
- How the hardening vulnerabilities were discovered by frontier AI models is not established.
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