CVE-2025-20199: Cisco IOS XE Privilege Escalation Flaw

CVE-2025-20199 Overview

CVE-2025-20199 is a local privilege escalation vulnerability in the command-line interface (CLI) of Cisco IOS XE Software. An authenticated attacker with privilege level 15 can escalate to root on the underlying operating system by supplying crafted input to specific configuration commands. Cisco raised the Security Impact Rating (SIR) to High because successful exploitation grants shell-level access to the underlying OS, enabling potentially undetected post-exploitation actions on affected network devices.

Critical Impact
Attackers who already hold privilege level 15 can break out of the IOS XE CLI sandbox to obtain root on the underlying Linux operating system, gaining full control of the network device outside normal auditing boundaries.

Affected Products

Cisco IOS XE Software (multiple 3.x, 16.x, and 17.x release trains up to 17.15.1w)
Cisco IOS XE 16.x releases (16.1.1 through 16.12.12)
Cisco IOS XE 17.x releases (17.1.1 through 17.15.x)

Discovery Timeline

2025-05-07 - CVE-2025-20199 published to NVD
2026-06-17 - Last updated in NVD database

Technical Details for CVE-2025-20199

Vulnerability Analysis

The vulnerability resides in how the IOS XE CLI parses and validates arguments supplied to specific configuration commands. Cisco IOS XE runs a Linux kernel underneath the IOS-style CLI, and configuration parsers translate user input into system-level operations. Insufficient input validation allows crafted arguments to break out of the CLI abstraction and execute in the context of the underlying operating system with root privileges.

The consequence is a complete separation-of-duty failure. A privilege level 15 administrator is expected to fully manage the device through the CLI, but not to obtain a shell on the underlying Linux OS. Root access on the host bypasses the AAA and audit controls that normally record administrative activity, allowing an operator or attacker who compromises credentials to install persistence, tamper with the file system, or disable logging.

Root Cause

The advisory attributes the flaw to insufficient input validation when processing specific configuration commands. Crafted input is not properly sanitized before being incorporated into an operation that executes at the OS layer, resulting in an escape from the CLI environment to root on the host OS (Cisco Security Advisory).

Attack Vector

Exploitation requires local access to the device CLI and valid credentials with privilege level 15 (enable/configuration mode). The attacker enters configuration mode and issues a specific configuration command containing crafted input. No user interaction beyond the attacker's own session is required, and the scope changes because the impact extends from the IOS XE control plane to the underlying Linux operating system.

No public proof-of-concept exploit is currently listed, and the vulnerability is not present on the CISA Known Exploited Vulnerabilities catalog. Refer to the Cisco Security Advisory for the vulnerable commands and fixed release matrix.

Detection Methods for CVE-2025-20199

Indicators of Compromise

Unexpected root shell processes on the underlying IOS XE Linux OS (for example, bash, sh, or scripts spawned outside the IOS XE process tree).
New or modified files under writable filesystem paths (/bootflash/, /harddisk/, /tmp/) that were not created by a documented software install or upgrade.
Configuration command invocations in AAA/TACACS+ accounting logs that were followed by device behavior inconsistent with the command's documented function.

Detection Strategies

Enable and centrally collect AAA command accounting for all privilege level 15 sessions, and alert on rare or non-standard configuration commands issued by administrators.
Ingest syslog and Cisco IOS XE audit records into a SIEM or data lake and hunt for configuration command patterns that correlate with subsequent unexplained process activity or file changes.
Compare running-config and startup-config against a known-good baseline on a scheduled basis to identify unauthorized modifications introduced through exploitation.

Monitoring Recommendations

Monitor for administrative logins from unexpected source IPs, jump hosts, or terminal servers, and flag privilege 15 sessions outside of change windows.
Track failed and successful enable transitions and configuration mode entries to identify credential misuse.
Correlate device configuration changes with change-management tickets, and investigate any privilege 15 activity without a matching authorized change.

How to Mitigate CVE-2025-20199

Immediate Actions Required

Identify all Cisco IOS XE devices in the environment and cross-reference their versions against the fixed releases listed in the Cisco advisory.
Upgrade affected devices to a Cisco-recommended fixed IOS XE release as soon as a maintenance window allows.
Rotate credentials for any account with privilege level 15 and review AAA policies to reduce the number of accounts holding full administrative rights.
Audit historical command accounting logs for evidence of the vulnerable configuration commands being issued.

Patch Information

Cisco has published fixed software releases in the Cisco Security Advisory cisco-sa-iosxe-privesc-su7scvdp. Consult the advisory's Fixed Software section for the specific IOS XE train and version that remediates CVE-2025-20199 on each hardware platform.

Workarounds

Cisco has not published a supported workaround; upgrading to a fixed release is the required remediation.
Restrict access to the CLI by enforcing strict AAA, TACACS+ command authorization, and network ACLs that limit which management hosts can reach VTY and console ports.
Limit privilege level 15 to a minimal set of accounts and require multi-factor authentication and jump-host access for all administrative sessions.

bash

# Example: harden management-plane access on Cisco IOS XE
# 1) Restrict VTY access to a dedicated management subnet
ip access-list standard MGMT-ACL
 permit 10.10.0.0 0.0.0.255
 deny   any log

line vty 0 4
 access-class MGMT-ACL in
 transport input ssh
 exec-timeout 5 0

# 2) Enforce AAA with TACACS+ command authorization and accounting
aaa new-model
aaa authentication login default group tacacs+ local
aaa authorization exec default group tacacs+ local
aaa authorization commands 15 default group tacacs+ local
aaa accounting commands 15 default start-stop group tacacs+

# 3) Verify running version and plan upgrade to a Cisco-listed fixed release
show version | include IOS-XE