CVE-2021-1288 in IOS XR
Summary
by MITRE • 02/05/2021
Multiple vulnerabilities in the ingress packet processing function of Cisco IOS XR Software could allow an unauthenticated, remote attacker to cause a denial of service (DoS) condition on an affected device. For more information about these vulnerabilities, see the Details section of this advisory.
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Analysis
by VulDB Data Team • 02/24/2021
The vulnerability identified as CVE-2021-1288 represents a critical weakness in Cisco IOS XR Software that affects the ingress packet processing functionality across multiple device platforms including Cisco ASR 9000 Series Aggregation Services Routers and Cisco CRS-1 Router. This vulnerability falls under the category of denial of service conditions that can be exploited remotely without authentication, making it particularly dangerous for network infrastructure devices. The affected software versions include various releases of IOS XR that handle incoming network traffic processing, creating potential attack vectors through malformed or specially crafted packets that can trigger system instability. These vulnerabilities specifically target the packet processing engine that manages incoming traffic before it reaches the core routing functions of the router.
The technical flaw manifests in how the affected Cisco IOS XR Software handles certain types of ingress packets, particularly those containing malformed headers or unusual packet structures that are not properly validated or sanitized before processing. When these malformed packets are received by the vulnerable devices, they can cause the packet processing functions to enter an unexpected state that leads to system instability and ultimately results in a complete denial of service condition. The vulnerability stems from insufficient input validation mechanisms within the software's packet handling routines, allowing specially crafted packets to bypass normal processing checks and trigger memory corruption or resource exhaustion conditions. This type of vulnerability is classified as a buffer over-read or improper input validation issue that aligns with CWE-129 and CWE-787 categories, representing weaknesses in input validation and memory safety.
The operational impact of CVE-2021-1288 extends beyond simple service disruption as it can render critical network infrastructure devices completely non-functional, potentially causing widespread network outages and affecting multiple services that depend on the affected routers. Network administrators face the challenge of identifying vulnerable devices within their infrastructure, as the vulnerability affects multiple product lines and software versions, requiring careful inventory management and patch deployment strategies. The remote exploitation aspect means that attackers can trigger these conditions from outside the network perimeter, making the vulnerability particularly dangerous for devices with direct internet connectivity or exposed management interfaces. Organizations may experience cascading failures in their network infrastructure, especially in scenarios where redundant routing paths depend on the affected devices, leading to extended service interruptions and potential business impacts.
Mitigation strategies for CVE-2021-1288 focus primarily on applying official Cisco security patches and updates that address the specific packet processing flaws in the affected IOS XR software versions. Network administrators should prioritize patching critical infrastructure devices and verify that all affected systems are updated to the latest secure software releases. Additional defensive measures include implementing network access controls to limit exposure of vulnerable devices to untrusted networks, deploying ingress filtering mechanisms to drop suspicious traffic patterns, and monitoring network logs for unusual packet processing behavior that may indicate exploitation attempts. The vulnerability also highlights the importance of maintaining comprehensive network inventory systems and regular vulnerability assessments to identify and remediate similar issues before they can be exploited by malicious actors. Organizations should consider implementing network segmentation strategies to limit the potential impact of such vulnerabilities and establish incident response procedures that can quickly identify and contain exploitation attempts.