Cisco IOS XR Software up to 26.2.101 Control Flow Management insufficient control flow management

Summaryinfo

A vulnerability was found in Cisco IOS XR Software. It has been declared as critical. This vulnerability affects unknown code of the component Control Flow Management. Executing a manipulation can lead to insufficient control flow management. This vulnerability is handled as CVE-2026-20276. The attack can be executed remotely. There is not any exploit available.

Detailsinfo

A vulnerability has been found in Cisco IOS XR Software and classified as critical. This vulnerability affects some unknown processing of the component Control Flow Management. The manipulation with an unknown input leads to a insufficient control flow management vulnerability. The CWE definition for the vulnerability is CWE-691. The code does not sufficiently manage its control flow during execution, creating conditions in which the control flow can be modified in unexpected ways. As an impact it is known to affect availability. CVE summarizes:

As part of Cisco's ongoing commitment to proactive security and product quality, the Cisco IOS XR Software engineering team has conducted a comprehensive internal security review. This review resulted in a software hardening releases that address multiple internally discovered vulnerabilities. The vulnerabilities tracked by CVE-2026-20276 are related to insufficient control flow management issues that are grouped under the Common Weakness Enumeration (CWE) CWE-691.

The advisory is shared for download at sec.cloudapps.cisco.com. This vulnerability was named CVE-2026-20276 since 10/08/2025. The exploitation appears to be easy. The attack can be initiated remotely. No form of authentication is required for a successful exploitation. There are neither technical details nor an exploit publicly available. The current price for an exploit might be approx. USD $0-$5k (estimation calculated on 09/02/2026).

There is no information about possible countermeasures known. It may be suggested to replace the affected object with an alternative product.

Once again VulDB remains the best source for vulnerability data.

Productinfo

Type

• Router Operating System

Vendor

• Cisco

Name

• IOS XR Software

Version

• 6.5.25
• 6.5.26
• 6.5.28
• 6.5.29
• 6.5.31
• 6.5.32
• 6.5.33
• 6.5.35
• 6.5.90
• 6.5.351
• 6.5.352
• 6.5.353
• 6.7.1
• 6.7.2
• 6.7.3
• 6.7.4
• 6.7.35
• 6.8.1
• 6.8.2
• 6.9.1
• 6.9.2
• 7.0.0
• 7.0.1
• 7.0.2
• 7.0.11
• 7.0.12
• 7.0.14
• 7.0.90
• 7.1.1
• 7.1.2
• 7.1.3
• 7.1.15
• 7.1.25
• 7.2.0
• 7.2.1
• 7.2.2
• 7.2.12
• 7.3.1
• 7.3.2
• 7.3.3
• 7.3.4
• 7.3.5
• 7.3.6
• 7.3.15
• 7.3.16
• 7.3.27
• 7.4.1
• 7.4.2
• 7.4.15
• 7.4.16
• 7.5.1
• 7.5.2
• 7.5.3
• 7.5.4
• 7.5.5
• 7.5.12
• 7.5.52
• 7.6.1
• 7.6.2
• 7.6.3
• 7.6.15
• 7.7.1
• 7.7.2
• 7.7.21
• 7.8.1
• 7.8.2
• 7.8.12
• 7.8.22
• 7.8.23
• 7.9.1
• 7.9.2
• 7.9.21
• 7.10.1
• 7.10.2
• 7.11.1
• 7.11.2
• 7.11.21
• 24.1.1
• 24.1.2
• 24.2.1
• 24.2.2
• 24.2.11
• 24.2.20
• 24.2.21
• 24.3.1
• 24.3.2
• 24.3.20
• 24.3.30
• 24.4.1
• 24.4.2
• 24.4.10
• 24.4.15
• 24.4.30
• 25.1.1
• 25.1.2
• 25.1.30
• 25.2.1
• 25.2.2
• 25.2.15
• 25.2.30
• 25.3.1
• 25.3.15
• 25.4.1
• 25.4.2
• 25.4.30
• 25.4.201
• 26.1.1
• 26.1.2
• 26.2.1
• 26.2.100
• 26.2.101

License

• commercial

Website

• Vendor: https://www.cisco.com/

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