Description
A vulnerability in the Intermediate System-to-Intermediate System (IS-IS) multi-instance routing feature of Cisco IOS XR Software could allow an unauthenticated, adjacent attacker to cause the IS-IS process to restart unexpectedly.
This vulnerability is due to insufficient input validation of ingress IS-IS packets. An attacker could exploit this vulnerability by sending crafted IS-IS packets to an affected device after forming an adjacency. A successful exploit could allow the attacker to cause the IS-IS process to restart unexpectedly, resulting in a temporary loss of connectivity to advertised networks and a denial of service (DoS) condition.
Note: The IS-IS protocol is a routing protocol. To exploit this vulnerability, an attacker must be Layer 2-adjacent to the affected device and must have formed an adjacency.
Affected products
| Vendor | Product | Affected | Fixed |
|---|---|---|---|
| Cisco | Cisco IOS XR Software | 7.8.1, 7.9.1, 7.10.1, 7.8.2, 7.8.22, 7.9.2, 7.11.1, 7.9.21, 7.10.2, 24.1.1, 7.11.2, 24.2.1, 24.1.2, 24.2.11, 24.3.1, 24.4.1, 24.2.2, 7.8.23, 7.11.21, 24.2.20, 24.3.2, 24.4.10, 25.1.1, 24.4.2, 24.3.20, 24.4.15, 25.2.1, 25.1.2, 24.3.30, 24.4.30, 24.2.21, 25.2.15 | — |
Advisories 2
- NCSC-2026-0094 Kwetsbaarheden verholpen in Cisco IOS XR NCSC-NL (Netherlands) · Mar 12, 2026
- WID-SEC-2026-0706 Cisco IOS XR: Mehrere Schwachstellen BSI CERT-Bund (WID) · Mar 11, 2026