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Warning: CISCO IOS XR Software for ASR 9000 Series routers – Denial of Service Vulnerability

Advisory #2023-28
Affected software: 
ASR 9000 Series Aggregation Services Routers only if they have a Lightspeed or Lightspeed-Plus-based line card installed
ASR 9902 Compact High-Performance Routers
ASR 9903 Compact High-Performance Routers
Incorrect handling of malformed BFD packets
CVE-2023-20049: 8.6 (HIGH)




An attacker could exploit this vulnerability by sending a crafted IPv4 bidirectional forwarding detection (BFD) packet to an affected device. A successful exploit could allow the attacker to cause line card exceptions or a hard reset, resulting in loss of traffic over that line card while the line card reloads.


A vulnerability in the bidirectional forwarding detection (BFD) hardware offload feature of Cisco IOS XR Software for Cisco ASR 9000 Series Aggregation Services Routers, ASR 9902 Compact High-Performance Routers, and ASR 9903 Compact High-Performance Routers could allow an unauthenticated, remote attacker to cause a line card to reset, resulting in a denial of service (DoS) condition.

Cisco has released software updates that address this vulnerability. There are workarounds that address this vulnerability.

Additional technical details, mitigation instructions and workaround instructions can be found in the Cisco Advisory with ID: cisco-sa-bfd-XmRescbT. (See references, below)

Recommended Actions

The CCB recommends applying the proposed software updates that address the vulnerability described in the Cisco advisory.

If, due to operational impact, mitigation is currently not possible, the CCB recommends applying the workaround, as detailed in the Cisco advisory.