Improper validation of specified type of input in Cisco IOS XR - CVE-2026-20074
Published: March 12, 2026
Vulnerability identifier: #VU123907
CSH Severity: Medium
CVSS v4: 7.1 [CVSS:4.0/AV:A/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N]
CVE-ID: CVE-2026-20074
CWE-ID: CWE-1287
Exploitation vector: Adjecent network
Exploit availability:
No public exploit available
Vulnerability details
The vulnerability allows a remote attacker to perform a denial of service attack.
The vulnerability exists due to improper input validation of ingress IS-IS packets in the Intermediate System-to-Intermediate System (IS-IS) multi-instance routing feature. A remote attacker on the local network can send specially crafted IS-IS packets to an affected device and perform a denial of service attack.
Affected software
Cisco IOS XR
How to mitigate CVE-2026-20074
Install updates from vendor's website.
Cisco IOS XR - addressed in versions 25.1.30, 25.2.2, 25.3.1, 25.4.1, 26.1.1