Cisco Patches High-Severity DoS Vulnerability in Enterprise Routers

March 9, 2023

Cisco has released patches for a high-severity denial-of-service (DoS) vulnerability in the IOS XR software for ASR 9000, ASR 9902, and ASR 9903 series enterprise routers. Tracked as CVE-2023-20049 (CVSS score of 8.6), the vulnerability impacts the bidirectional forwarding detection (BFD) hardware offload feature for the platform and can be exploited remotely, without authentication. According to Cisco, 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.

As a workaround, Cisco recommends disabling the BFD hardware offload feature, which can be done by removing all hw-module bfw-hw-offload enable commands and resetting the line card. Patches for this vulnerability were included in IOS XR software versions 7.5.3, 7.6.2, and 7.7.1. Additionally, Cisco also released patches for an information disclosure vulnerability in the GRand Unified Bootloader (GRUB) for IOS XR software, tracked as CVE-2023-20064.

"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," said Cisco. The tech giant has not reported any of these vulnerabilities being exploited in attacks.

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