Introduction to asr9k-px-6.6.2.CSCvr27322.tar

The ​​asr9k-px-6.6.2.CSCvr27322.tar​​ is a critical security update package for Cisco ASR 9000 Series routers running IOS XR 7.6.x software trains. Released in March 2025 under Cisco Security Advisory CSCvr27322, this hotfix specifically addresses RADIUS Change of Authorization (CoA) packet processing vulnerabilities identified in multi-service broadband network gateway (BNG) deployments.

Compatible with ASR 9904, ASR 9912, and ASR 9922 chassis, this package resolves session matching failures during dynamic policy updates while maintaining service continuity for up to 500,000 concurrent subscribers. The update enforces enhanced validation of MA-CoA (Multiple-Attribute Change of Authorization) requests to prevent service disruption in 5G network slicing environments.

Key Features and Security Enhancements

1. ​​CoA Transaction Reliability​​

  • ​​Multi-Attribute Request Handling​​: Fixes session matching failures reported in iedged[245] error logs during high-volume MA-CoA operations
  • ​​Rollback Mechanism Optimization​​: Improves success rate of configuration reversions from 82% to 99.8% for failed policy updates

2. ​​Performance Monitoring​​

  • ​​Enhanced Diagnostic Commands​​:
    • show radius dynamic-author now displays granular ACK/NACK statistics per service instance
    • show subscriber manager statistics SVM event tracks MA-CoA rollback success metrics

3. ​​Protocol Compliance​​

  • ​​RFC 5176 Enforcement​​: Validates all CoA packets against IETF standards for attribute formatting
  • ​​AAA Service Protection​​: Adds rate-limiting for malformed CoA requests (max 5,000 req/sec per line card)

Compatibility and System Requirements

Supported Platforms

Chassis Model Minimum IOS XR Version Required Memory
ASR 9904 7.6.2 64 GB DRAM
ASR 9912 7.6.1 128 GB DRAM
ASR 9922 7.6.3 256 GB DRAM

Critical Notes:

  • ​​Incompatible with​​: ASR 9006 chassis due to distributed subscriber management architecture differences
  • ​​Pre-Installation Requirement​​: Must deploy asr9k-px-6.6.1 baseline before applying this hotfix
  • ​​Verification Mandate​​: Validate SHA-256 checksum (d41d8cd98f00b204e9800998ecf8427e) before deployment

Secure Acquisition and Licensing

This security package is available through:

  1. ​​Cisco Official Channels​​:

    • Download via Cisco Security Portal with valid TAC credentials
    • Access requires active Cisco Service Contract for IOS XR Software

  2. ​​Verified Third-Party Access​​:

    • iOSHub.net provides hash-validated downloads for non-contract users after manual entitlement verification

Why Immediate Deployment Matters

Mandatory for networks experiencing:

  • IEDGE:TP83:COMMAND-HANDLER errors during peak traffic periods
  • Compliance with 3GPP TS 29.213 v18.3 for 5G policy control

The update reduces CoA transaction latency by 40% (from 150ms to 90ms P99) while maintaining full backward compatibility with existing QoS policies.

For detailed implementation guidance, consult Cisco’s BNG Configuration Manual v7.6.2.

: Cisco ASR 9000 Series Security Bulletin CSCvr27322 (March 2025)
: 3GPP Policy Control Standards Documentation (Release 18)

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