Cisco has disclosed a serious security vulnerability affecting its IOS and IOS XE Software that could allow attackers to execute remote code or crash affected devices.
The flaw, tracked as CVE-2025-20352, resides in the Simple Network Management Protocol (SNMP) subsystem and carries a CVSS score of 7.7, marking it as a high-severity threat.
Overview of the Vulnerability
The vulnerability stems from a stack overflow condition in the SNMP subsystem that processes network management traffic.
What makes this flaw particularly concerning is its dual-threat nature. Attackers with low-level privileges can exploit it to trigger a denial of service condition, forcing affected devices to reload and disrupting network operations.
| CVE ID | CVSS 3.1 Score | CWE | Impact |
| CVE-2025-20352 | 7.7 (High) | CWE-121 (Stack-based Buffer Overflow) | Denial of Service (DoS) or Remote Code Execution (RCE) |
More alarmingly, attackers with high-level administrative access can leverage the same flaw to execute arbitrary code with root privileges, potentially gaining complete control over the compromised system.
To exploit this vulnerability, an attacker must send a specially crafted SNMP packet to the target device over IPv4 or IPv6 networks.
The attack requires either SNMPv2c or earlier read-only community strings, or valid SNMPv3 user credentials.
For remote code execution attacks, administrative or privilege 15 credentials are additionally required.
The vulnerability affects all versions of SNMP, making it a widespread concern for organizations using Cisco networking equipment.
All Cisco devices running vulnerable releases of IOS Software or IOS XE Software with SNMP enabled are susceptible to this attack.
Organizations can determine if their devices are vulnerable by checking their SNMP configuration using specific CLI commands.
Devices with SNMPv1, v2c, or v3 enabled should be considered at risk unless they have explicitly excluded the affected object identifier.
Cisco has confirmed that its IOS XR Software and NX-OS Software products are not affected by this vulnerability.
Cisco has released software updates that fully address this vulnerability, and organizations are strongly urged to upgrade immediately.
While no complete workarounds exist, administrators can implement temporary mitigation measures by restricting SNMP access to trusted users only and disabling the affected object identifiers through specific configuration commands.
However, these mitigations may impact device management capabilities through SNMP, including discovery and hardware inventory functions.
The vulnerability was first published on September 24, 2025, as part of Cisco’s semiannual security advisory bundled publication.
Organizations can use Cisco’s Software Checker tool to identify affected releases and determine appropriate fixed software versions for their specific deployments.
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