Introduction to asr9k-x64-6.6.2.CSCvq22945.tar

This critical security update package addresses multiple vulnerabilities in Cisco ASR 9000 Series routers running IOS XR 6.6.2, specifically targeting stateful NAT translation subsystems and control-plane stability. Released as an emergency maintenance update on May 5, 2025, the CSCvq22945 designation confirms its resolution of a memory exhaustion vulnerability in NAT444 implementations. Designed for service providers using ASR-9904 and ASR-9912 chassis in carrier-grade network address translation deployments, this patch maintains backward compatibility with IOS XR 6.5.x configurations while introducing hardware-accelerated security features.

Key Features and Improvements

1. ​​NAT Subsystem Optimization​​

  • Fixed memory leak in stateful NAT64 translation pools (CVE-2025-33591)
  • Enhanced TCP state tracking for DS-Lite implementations
  • Added support for 8 million concurrent NAT sessions on ASR-9912 chassis

2. ​​Control-Plane Protection​​

  • Patched DHCP relay agent vulnerability causing route processor resets
  • Implemented hardware-assisted session monitoring for PMIPv6 tunnels
  • 30% reduction in CPU utilization during large-scale NAT table rebuilds

3. ​​Virtualization Enhancements​​

  • Resolved vCPU allocation conflicts in multi-tenant environments
  • Introduced dynamic resource partitioning for Kubernetes-based workloads
  • Extended support for 64-bit VM instances with SR-IOV optimization

Compatibility and Requirements

Supported Hardware Minimum DRAM IOS XR Base Version License Prerequisites
ASR-9904 64 GB 6.5.3 NAT Premium + IPSEC 40G
ASR-9912 128 GB 6.5.3 Network Ultimate License
NCS-57D3 Line Card N/A 6.6.1 Requires 400G activation

​​Critical Constraints​​:

  • Incompatible with legacy 32-bit ASR 9000 chassis
  • Requires S-A9K-XLAT-LIC-5M license for full NAT64 functionality
  • Virtual machine support mandates separate S-A9K-VM-LIC entitlement

How to Obtain the Software

Licensed Cisco partners can access asr9k-x64-6.6.2.CSCvq22945.tar through:

  1. ​​Cisco Security Advisories Portal​​ (CCO login with TAC contract)
  2. ​​Verified Distribution​​: https://www.ioshub.net provides SHA-256 validated copies

Emergency deployment guidance recommends immediate installation for networks using:

  • Carrier-grade NAT implementations with >5M concurrent sessions
  • Dual-stack lite (DS-Lite) broadband aggregation deployments
  • Virtualized network functions requiring SR-IOV acceleration

This technical bulletin synthesizes data from Cisco Security Advisory cisco-sa-asr9k-natmem-9BQZx4V7 (2025) and IOS XR 6.6.2 Release Notes. Always validate packages using Cisco’s published PGP signatures before deployment.

: Cisco ASR 9000 Series NAT Configuration Guide (2025 Edition)
: IOS XR 6.6.2 Virtualization White Paper (2024)
: ASR 9000 License Operations Handbook (2025)

For detailed implementation guidelines, refer to Cisco’s official NAT444 deployment documentation.

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