Critical Flaw in Cisco IOS XR Allows Unauthorized Code Execution, Router Crashes

Cisco Patches Critical Flaw in IOS XE and XR Software

A critical vulnerability has been discovered in Cisco's IOS XE and XR software, which could allow an attacker to remotely execute arbitrary code on affected devices. The flaw, identified as CVE-2025-20115, has been assigned a severity rating of 9.8 out of 10 by the Common Vulnerability Scoring System (CVSS).

According to Cisco, the vulnerability is due to a buffer overflow in the affected software's implementation of the TCP/IP protocol. An attacker could exploit this flaw by sending a specially crafted packet to an affected device, which could then execute arbitrary code with elevated privileges.

The vulnerability affects Cisco's IOS XE and XR software, which is used in a wide range of devices, including routers, switches, and other network equipment. Cisco has released patches for the vulnerability, and users are advised to apply the updates as soon as possible to prevent exploitation.

In a statement, Cisco said, "Cisco has released software updates that address this vulnerability. Customers are advised to apply these updates as soon as possible to prevent exploitation. Cisco is not aware of any publicly available exploit code for this vulnerability."

The discovery of the vulnerability was made by a team of security researchers at Synack, a leading provider of bug bounty and penetration testing services. The researchers worked with Cisco to identify and develop a fix for the flaw, which was then released as part of Cisco's regular software update cycle.

The discovery of the vulnerability highlights the importance of regular software updates and patches in preventing exploitation of critical flaws. It also underscores the need for continued investment in bug bounty and penetration testing programs, which can help identify and remediate vulnerabilities before they can be exploited by attackers.