Active Exploitation of Cisco SNMP Vulnerability CVE-2025-20352 in IOS and IOS XE Devices
A critical security vulnerability, CVE-2025-20352, has been identified in the Simple Network Management Protocol (SNMP) subsystem of Cisco IOS and IOS XE software, affecting a wide range of Cisco networking devices. This stack overflow flaw allows remote attackers with valid SNMP credentials to send specially crafted SNMP packets over IPv4 or IPv6, potentially causing denial-of-service (DoS) by forcing device reloads or, in more severe cases, enabling remote code execution as root. The vulnerability impacts all SNMP versions (v1, v2c, v3) and has been confirmed to affect both legacy and modern modular Cisco operating systems, including Meraki MS390 and Catalyst 9300 Series Switches running Meraki CS 17 and earlier. Reports indicate that up to 2 million devices globally, including those operated by ISPs and cloud providers, are potentially exposed to this vulnerability. The flaw was discovered during a Cisco Technical Assistance Center (TAC) support case and has already been exploited in the wild, prompting its addition to the CISA Known Exploited Vulnerabilities (KEV) catalog on September 29th, 2025. The exploitation of this vulnerability represents a significant escalation, as attackers have demonstrated the ability to gain administrator-level credentials and full device compromise. Rockwell Automation has issued an advisory confirming that its Lifecycle Services, specifically the Industrial Data Center (IDC) with Cisco Switching (Generations 1–5), are affected by this vulnerability. Rockwell has provided guidance on corrected software versions and available workarounds to mitigate the risk. The vulnerability poses a substantial threat to the backbone of enterprise, industrial, and service provider networks, given the widespread deployment of affected Cisco devices. Cisco’s response to the incident was initiated only after evidence of active exploitation emerged, underscoring the urgency of patching and mitigation. Organizations are strongly advised to update to the corrected Cisco software versions as soon as possible and to implement any recommended workarounds to reduce exposure. The incident highlights the ongoing risks associated with SNMP-enabled network infrastructure and the importance of credential management and network segmentation. Security teams should prioritize the identification of vulnerable devices and monitor for signs of exploitation. The rapid exploitation and large attack surface associated with CVE-2025-20352 make it a high-priority threat for organizations relying on Cisco networking equipment.
Timeline
Oct 2, 2025
Rockwell warns Lifecycle Services is affected by Cisco CVE-2025-20352
Rockwell Automation published an advisory stating that its Lifecycle Services is vulnerable to Cisco CVE-2025-20352. This expanded the story beyond Cisco's own products by identifying downstream exposure in a vendor service offering.
Oct 2, 2025
Cisco releases fixes for CVE-2025-20352
Cisco released software updates to address CVE-2025-20352, including IOS XE version 17.15.4a, and recommended immediate patching, restricting SNMP access, and increasing monitoring. The issue was described as affecting a large number of devices globally, including certain Meraki MS390 and Catalyst 9300 platforms running vulnerable software.
Oct 2, 2025
Cisco SNMP flaw CVE-2025-20352 is exploited in the wild
A critical stack overflow vulnerability in the SNMP subsystem of Cisco IOS and IOS XE, tracked as CVE-2025-20352, was reported as being actively exploited in the wild. The flaw affects all SNMP versions on impacted devices and can allow an authenticated remote attacker to cause denial of service or execute code as root using stolen or mismanaged SNMP credentials.
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