CVE-2025-20196 Overview
CVE-2025-20196 is a denial of service (DoS) vulnerability in the Cisco IOx application hosting environment of Cisco IOS Software and Cisco IOS XE Software. An unauthenticated, remote attacker can send crafted HTTP requests to an affected device and cause the IOx process to stop responding. Recovery requires a manual restart of the IOx process, disrupting hosted applications until an administrator intervenes.
The issue is tracked under [CWE-307] and impacts a broad range of Cisco routing, wireless, and industrial platforms that support IOx application hosting. Cisco published a security advisory on May 7, 2025.
Critical Impact
Remote attackers can disrupt hosted IOx applications on Cisco IOS and IOS XE devices without authentication, requiring manual intervention to restore service.
Affected Products
- Cisco IOS XE Software (multiple versions from 16.1.1 through 17.15.2c)
- Cisco Industrial Routers (807, 809, 829 ISR, CGR1000, IR510 WPAN, IC3000)
- Cisco Catalyst 9100 series Access Points (9105, 9115, 9117, 9120, 9124, 9130, 9136, 9162, 9164, 9166)
Discovery Timeline
- 2025-05-07 - CVE-2025-20196 published to NVD
- 2025-05-07 - Cisco publishes security advisory cisco-sa-iox-dos-95Fqnf7b
- 2026-06-17 - Last updated in NVD database
Technical Details for CVE-2025-20196
Vulnerability Analysis
The vulnerability resides in the Cisco IOx application hosting environment, a framework that allows customers to develop and deploy IoT and edge applications directly on Cisco networking hardware. The IOx service exposes an HTTP interface used for application management and orchestration. Improper handling of specific HTTP request patterns causes the IOx process to hang and stop servicing legitimate requests.
Because the attack targets the network-facing management plane of the IOx subsystem, no authentication or user interaction is required. Only the availability of hosted IOx applications is impacted; confidentiality and integrity of underlying IOS and IOS XE traffic forwarding are not affected. However, applications running under IOx remain unavailable until an administrator manually restarts the IOx process.
Root Cause
Cisco classifies the underlying weakness as [CWE-307] (Improper Restriction of Excessive Authentication Attempts) in the NVD entry, and the advisory attributes the failure to improper handling of HTTP requests within the IOx application hosting stack. Malformed or unexpected request sequences drive the IOx service into an unresponsive state rather than gracefully rejecting the input.
Attack Vector
An attacker with network reachability to the IOx HTTP management interface sends crafted HTTP requests to the affected device. Successful exploitation halts the IOx process. The device continues to forward traffic, but hosted IOx applications become unavailable until manual recovery.
No verified public exploit code or proof-of-concept is available at time of writing. See the Cisco Security Advisory for authoritative technical details.
Detection Methods for CVE-2025-20196
Indicators of Compromise
- IOx process transitions to an unresponsive state and hosted applications become unreachable following inbound HTTP traffic to the IOx management interface.
- Failed or timed-out administrative requests to IOx endpoints such as those used by ioxclient or the Local Manager UI.
- Syslog entries indicating IOx service failures or the need to manually restart the IOx daemon.
Detection Strategies
- Monitor Cisco IOS XE syslog output for IOx process crashes, restart events, and application hosting errors.
- Baseline expected sources of HTTP traffic to the IOx management interface and alert on unexpected external clients.
- Correlate spikes of malformed HTTP requests to IOx endpoints with subsequent IOx service availability drops.
Monitoring Recommendations
- Track the operational state of IOx via show iox-service and show app-hosting list on a scheduled interval and alert on abnormal transitions.
- Forward device syslog and SNMP traps to a centralized SIEM or data lake for correlation with network telemetry.
- Enable NetFlow or IPFIX on management interfaces to detect anomalous HTTP request volumes destined for IOx.
How to Mitigate CVE-2025-20196
Immediate Actions Required
- Review the Cisco Security Advisory cisco-sa-iox-dos-95Fqnf7b and identify affected devices in inventory.
- Restrict network access to the IOx HTTP management interface to trusted administrative hosts using infrastructure ACLs and control plane policing.
- Upgrade affected Cisco IOS XE devices to a fixed release as identified by Cisco for each platform.
Patch Information
Cisco has published fixed software releases in the advisory cisco-sa-iox-dos-95Fqnf7b. Administrators should consult the Cisco advisory to determine the first fixed release for each specific platform and IOS XE train, then plan upgrades through standard Cisco software download and staging processes.
Workarounds
- Disable IOx application hosting on devices that do not require it using no iox in global configuration mode.
- Apply infrastructure ACLs to permit access to the IOx management interface only from authorized management subnets.
- Place the device management plane on a dedicated out-of-band VRF to reduce exposure to untrusted networks.
# Example: restrict IOx management access with an infrastructure ACL
ip access-list extended IOX-MGMT-ACL
permit tcp 10.10.0.0 0.0.255.255 any eq 8443
deny tcp any any eq 8443 log
permit ip any any
!
interface GigabitEthernet0/0/0
ip access-group IOX-MGMT-ACL in
!
! Disable IOx entirely on devices where application hosting is not required
configure terminal
no iox
end
Disclaimer: This content was generated using AI. While we strive for accuracy, please verify critical information with official sources.
