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Vulnerability Exposes Cisco Enterprise Routers to Disruptive Attacks

Cisco has released patches for a high-severity DoS vulnerability in IOS XR software for several enterprise-grade routers.

Cisco this week announced 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.

On vulnerable devices with the BFD hardware offload feature enabled, malformed BFD packets are incorrectly handled, allowing an attacker to send crafted IPv4 BFD packets to the configured IPv4 address and trigger the flaw.

“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,” Cisco explains in an advisory.

As a workaround, the tech giant 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.

The security defect impacts ASR 9000 series aggregation services routers with a Lightspeed or Lightspeed-Plus-based line card installed and ASR 9902 and ASR 9903 compact high-performance routers.

Patches for this vulnerability were included in IOS XR software versions 7.5.3, 7.6.2, and 7.7.1.

This week, Cisco also announced patches for an information disclosure vulnerability in the GRand Unified Bootloader (GRUB) for IOS XR software. Tracked as CVE-2023-20064, the vulnerability can be exploited by unauthenticated attackers that have physical access to the device.

The tech giant says it is not aware of any of these vulnerabilities being exploited in attacks. Additional details can be found on Cisco’s product security page.

Related: Cisco Patches Critical Vulnerability in IP Phones

Related: Cisco Patches High-Severity Vulnerabilities in ACI Components

Related: Critical Vulnerability Patched in Cisco Security Products

Written By

Ionut Arghire is an international correspondent for SecurityWeek.

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