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9.8
CVE-2026-76459: Cisco NX-OS could overwrite memory and crash
CVE-2026-76459 · published 2 days ago
Summary
Cisco's NX-OS operating system and the Unified Computing System running in ACI mode contain coding mistakes that can write data outside of its intended area. This could cause the device to behave unpredictably or stop working, potentially affecting network reliability. Apply the October 2026 software hardening update from Cisco as soon as possible to fix the issue.
What to do
The CVE record does not list a fixed version. Check the vendor's site or the advisory links below - a fix may already be released.
Affected software
| Vendor | Product | Affected versions |
|---|---|---|
| cisco | cisco nx-os software | 8.2(5) |
| cisco | cisco nx-os system software in aci mode | 15.2(1g) |
| cisco | cisco unified computing system (managed) | 4.0(1a) |
Original advisory text
Cisco NX-OS Software Security Hardening Release: October 2026 - Out-of-bounds Write Vulnerabilities
As part of Cisco's ongoing commitment to proactive security and product quality, the Cisco NX-OS engineering team has conducted a comprehensive internal security review. This review resulted in a software hardening release that addresses multiple internally discovered vulnerabilities.
The vulnerabilities tracked by CVE-2026-76459 are related to out-of-bounds write issues that are grouped under the Common Weakness Enumeration (CWE) CWE-787.
The vulnerabilities tracked by CVE-2026-76459 are related to out-of-bounds write issues that are grouped under the Common Weakness Enumeration (CWE) CWE-787.
Internet-facing
14 days
Internal
At next upgrade
- Not known to be exploited
- Needs hands-on effort to exploit
- Gives an attacker full control
Severity
9.8
Critical
Type
CWE-787Out-of-bounds Write
Timeline
Published7 Oct 2026
Updated9 Oct 2026
First seen7 Oct 2026
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