Answer in brief
CVE-2026-20074 records a High severity (CVSS 7.4) vulnerability in Cisco IOS XR Software Multi-Instance Intermediate System-to-Intermediate System Denial of Service Vulnerability. The current sources do not mark it as known exploited. The current feed maps Cisco/Cisco IOS XR Software (generic). Check affected ranges and fixed versions before updating.
Analysis pending evidence review
HOL Guard separates source facts from reviewed analysis. See the methodology.
CVSS is 7.4. The current sources do not mark it as known exploited. Treat this as a source-backed prioritization signal, not a statement about your environment.
Analysis status
Analysis pending evidence review
Factual feed record only; HOL analysis is not approved for indexing. Read the methodology.
The current feed maps Cisco/Cisco IOS XR Software (generic). Check affected ranges and fixed versions before updating.
| Package | Affected range | Fixed version |
|---|---|---|
| Cisco/Cisco IOS XR Softwaregeneric | 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 | Not reported |
Published upstream
Mar 11, 2026
Evidence: source:cvelist:source_dates:source-dates:recordSource modified
Jul 8, 2026
Evidence: source:cvelist:source_dates:source-dates:recordFirst seen by HOL
Jul 8, 2026
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.
Quoted source text, attributed separately from HOL analysis.
Answer in brief
CVE-2026-20074 records a High severity (CVSS 7.4) vulnerability in Cisco IOS XR Software Multi-Instance Intermediate System-to-Intermediate System Denial of Service Vulnerability. The current sources do not mark it as known exploited. The current feed maps Cisco/Cisco IOS XR Software (generic). Check affected ranges and fixed versions before updating.
Analysis pending evidence review
HOL Guard separates source facts from reviewed analysis. See the methodology.
CVSS is 7.4. The current sources do not mark it as known exploited. Treat this as a source-backed prioritization signal, not a statement about your environment.
Analysis status
Analysis pending evidence review
Factual feed record only; HOL analysis is not approved for indexing. Read the methodology.
The current feed maps Cisco/Cisco IOS XR Software (generic). Check affected ranges and fixed versions before updating.
| Package | Affected range | Fixed version |
|---|---|---|
| Cisco/Cisco IOS XR Softwaregeneric | 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 | Not reported |
Published upstream
Mar 11, 2026
Evidence: source:cvelist:source_dates:source-dates:recordSource modified
Jul 8, 2026
Evidence: source:cvelist:source_dates:source-dates:recordFirst seen by HOL
Jul 8, 2026
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.
Quoted source text, attributed separately from HOL analysis.