CVE-2020-26070: Cisco IOS XR Software for Cisco ASR 9000 Series Aggregation Services Routers Slow Path Forwarding Denial of Service Vulnerability

Severity: high (CVSS 8.6 v3.1)
Exploited in the wild: not listed in CISA KEV
EPSS: 1.9% probability of exploitation in the next 30 days
Public exploit or detection template: none known
Published: 2020-11-12 · updated 2026-06-17
Weakness: CWE-404

Description

A vulnerability in the ingress packet processing function of Cisco IOS XR Software for Cisco ASR 9000 Series Aggregation Services Routers could allow an unauthenticated, remote attacker to cause a denial of service (DoS) condition on an affected device. The vulnerability is due to improper resource allocation when an affected device processes network traffic in software switching mode (punted). An attacker could exploit this vulnerability by sending specific streams of Layer 2 or Layer 3 protocol data units (PDUs) to an affected device. A successful exploit could cause the affected device to run out of buffer resources, which could make the device unable to process or forward traffic, resulting in a DoS condition. The device would need to be restarted to regain functionality.

Affected products

Cisco IOS XR Software: before 6.7.2; from 7.1.0 before 7.1.2 — fixed in 6.7.2, 7.1.2

How to fix

Upgrade to a fixed version: Cisco IOS XR Software 6.7.2, 7.1.2. Check the vendor advisory for mitigations.

References

Get alerted when CVE-2020-26070 or the next vulnerability affects your stack