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.
Default status is the baseline for the product, each version can override it (e.g. patched versions marked unaffected).
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| Cisco | Cisco IOS XR Software | unknown |
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Project Subscriptions
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Solution
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Workaround
No workaround given by the vendor.
Wed, 11 Mar 2026 18:15:00 +0000
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| Metrics |
ssvc
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Wed, 11 Mar 2026 17:00:00 +0000
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| 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. | |
| Title | Cisco IOS XR Software Multi-Instance Intermediate System-to-Intermediate System Denial of Service Vulnerability | |
| Weaknesses | CWE-1287 | |
| References |
| |
| Metrics |
cvssV3_1
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Projects
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MITRE
Status: PUBLISHED
Assigner: cisco
Published:
Updated: 2026-03-11T17:20:21.640Z
Reserved: 2025-10-08T11:59:15.362Z
Link: CVE-2026-20074
Vulnrichment
Updated: 2026-03-11T17:14:25.185Z
NVD
Status : Received
Published: 2026-03-11T17:16:55.470
Modified: 2026-03-11T17:16:55.470
Link: CVE-2026-20074
Redhat
No data.
OpenCVE Enrichment
No data.