CVE-2023-20135: Cisco IOS XR

High severity, CVSS 7.0. EPSS: 0.1% chance of exploitation in the next 30 days.

A vulnerability in Cisco IOS XR Software image verification checks could allow an authenticated, local attacker to execute arbitrary code on the underlying operating system. This vulnerability is due to a time-of-check, time-of-use (TOCTOU) race condition when an install query regarding an ISO image is performed during an install operation that uses an ISO image. An attacker could exploit this vulnerability by modifying an ISO image and then carrying out install requests in parallel. A successful exploit could allow the attacker to execute arbitrary code on an affected device.

Affected products

• Cisco IOS XR: from 7.5.2, before 7.6 (fixed in 7.6); from 7.7, before 7.10.1 (fixed in 7.10.1)

Published 2023-09-13. Last modified 2026-06-17.