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CVE-2026-76459: Cisco NX-OS Software Security Hardening Release: October 2026 - Out-of-bounds Write Vulnerabilities

• Severity: critical (CVSS 9.8 v3.1)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 0.3% probability of exploitation in the next 30 days
• Public exploit or detection template: none known
• Published: 2026-10-07 · updated 2026-10-09
• Weakness: CWE-787

Description

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.

Affected products

• Cisco NX-OS: 8.2(5), 7.3(5)D1(1), 8.4(2), 8.4(3), 9.2(3), 8.2(1) (+201)
• Cisco Unified Computing System (Managed): 4.0(1a), 4.1(1d), 4.0(4f), 4.0(4c), 4.0(2b), 4.1(2a) (+99)

In the news

• Cisco Advance Notification for Publication of October 7, 2026, Security Advisories
• Cisco NX-OS Software Security Hardening Release: October 2026

References

• https://sec.cloudapps.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-hardening-nxosw1-cWzSbtR

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