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

Summary

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 versions

• Cisco Cisco NX-OS Software

  8.2(5), 7.3(5)D1(1), 8.4(2), 8.4(3), 9.2(3), 8.2(1), 7.3(1)D1(1), 9.2(2v), 7.3(0)D1(1), 7.3(4)D1(1), 9.2(1), 9.2(2t), 9.2(3y), 9.3(2), 7.3(1)DY(1), 8.1(1), 8.2(2), 8.3(2), 7.3(2)D1(3a), 9.2(4), 8.1(2), 7.3(3)D1(1), 8.2(3), 8.3(1), 8.4(1), 8.1(1b), 7.3(0)DX(1), 7.3(2)D1(1), 9.3(1), 7.3(2)D1(2), and 116 more

• Cisco Cisco NX-OS System Software in ACI Mode

  15.2(1g), 15.2(2e), 15.2(2f), 15.2(2g), 15.2(2h), 15.2(3f), 15.2(3e), 15.2(3g), 15.2(4d), 15.2(4e), 15.2(5c), 15.2(5d), 16.0(1g), 15.2(5e), 15.2(4f), 15.2(6e), 15.2(6h), 16.0(1j), 15.2(6g), 15.2(7f), 15.2(7g), 16.0(2h), 15.2(8d), 16.0(2j), 15.2(8e), 16.0(3d), 16.0(3e), 15.2(8f), 15.2(8g), 15.3(1d), and 31 more

• Cisco Cisco Unified Computing System (Managed)

  4.0(1a), 4.1(1d), 4.0(4f), 4.0(4c), 4.0(2b), 4.1(2a), 4.0(4a), 4.0(4e), 4.0(4h), 4.0(2a), 4.1(1c), 4.0(1b), 4.1(1e), 4.0(4d), 4.0(4b), 4.0(2e), 4.1(1a), 4.0(4g), 4.0(1d), 4.0(1c), 4.0(4i), 4.0(2d), 4.1(1b), 4.1(2b), 4.0(4k), 4.1(3a), 4.1(3b), 4.1(2c), 4.0(4l), 4.1(4a), and 75 more

References 1