This week, Cisco announced patches for a high-severity denial-of-service (DoS) vulnerability in IOS XR software for the ASR 9000, ASR 9902, and ASR 9903 series enterprise routers.
Registered as CVE-2023-20049 (CVSS score of 8.6), the vulnerability affects the Bidirectional Forwarding Detection (BFD) hardware offload function for the platform and can be exploited remotely, without authentication.
On vulnerable devices with the BFD hardware offload feature enabled, malformed BFD packets are handled incorrectly, 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 on that line card while it reloads,” Cisco explains in an advisory.
As a workaround, the tech giant recommends disabling the BFD hardware download feature, which can be done by removing everything hw-module bfw-hw-enable download commands and reset the line card.
The security flaw affects ASR 9000 series aggregation services routers with a Lightspeed or Lightspeed-Plus-based line card installed and ASR 9902 and ASR 9903 high-performance compact routers.
Patches for this vulnerability were included in versions 7.5.3, 7.6.2, and 7.7.1 of the IOS XR software.
This week, Cisco also announced patches for an information disclosure vulnerability in the GRand Unified Bootloader (GRUB) for the IOS XR software. Tracked as CVE-2023-20064, the vulnerability can be exploited by unauthenticated attackers who have physical access to the device.
The tech giant says it’s not aware of any of these vulnerabilities being exploited in attacks. Additional details can be found on the Cisco Product Security page.
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