CVE-2026-20074 A vulnerability in the Intermediate System-to-Intermediate System (IS-IS) multi-instance routing feature of Cisco IOS XR…
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 and versions
| Product | Affected versions | Fixed in |
|---|---|---|
| Cisco IOS XR Software 25.2 | 25.2.1 → 25.2.15 | No fix stated |
| Cisco IOS XR Software 25.1 | 25.1.1 → 25.1.2 | No fix stated |
| Cisco IOS XR Software 24.4 | 24.4.1 → 24.4.30 | No fix stated |
| Cisco IOS XR Software 24.3 | 24.3.1 → 24.3.30 | No fix stated |
| Cisco IOS XR Software 24.2 | 24.2.1 → 24.2.21 | No fix stated |
| Cisco IOS XR Software 24.1 | 24.1.1 → 24.1.2 | No fix stated |
| Cisco IOS XR Software 7.11 | 7.11.1 → 7.11.21 | No fix stated |
| Cisco IOS XR Software 7.10 | 7.10.1 → 7.10.2 | No fix stated |
| Cisco IOS XR Software 7.9 | 7.9.1 → 7.9.21 | No fix stated |
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| Product | Affected versions | Fixed in |
|---|---|---|
| Cisco IOS XR Software 7.8 | 7.8.1 → 7.8.23 | No fix stated |
References
- cisco-sa-isis-dos-kDMxpSzK sec.cloudapps.cisco.com
Timeline
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