CVEs / CVE-2025-20352

CVE-2025-20352: Cisco IOS and IOS XE Software SNMP Denial of Service and Remote Code Execution Vulnerability

• Known exploited in the CISA KEV catalog since 29 Sep 2025
• high 7.7 CVSS 3.1 (from the CNA)
• EPSS 41.5% chance of exploitation in the next 30 days, higher than 98% of CVEs (30 Oct 2026)
• Last changed at its sources 26 Sep 2026

Summary

Cisco IOS and IOS XE contains a stack-based buffer overflow vulnerability in the Simple Network Management Protocol (SNMP) subsystem that could allow for denial of service or remote code execution. A successful exploit could allow a low-privileged attacker to cause the affected system to reload, resulting in a DoS condition, or allow a high-privileged attacker to execute arbitrary code as the root user and obtain full control of the affected system.

Description

A vulnerability in the Simple Network Management Protocol (SNMP) subsystem of Cisco IOS Software and Cisco IOS XE Software could allow the following: An authenticated, remote attacker with low privileges could cause a denial of service (DoS) condition on an affected device that is running Cisco IOS Software or Cisco IOS XE Software. To cause the DoS, the attacker must have the SNMPv2c or earlier read-only community string or valid SNMPv3 user credentials. An authenticated, remote attacker with high privileges could execute code as the root user on an affected device that is running Cisco IOS XE Software. To execute code as the root user, the attacker must have the SNMPv1 or v2c read-only community string or valid SNMPv3 user credentials and administrative or privilege 15 credentials on the affected device. An attacker could exploit this vulnerability by sending a crafted SNMP packet to an affected device over IPv4 or IPv6 networks. This vulnerability is due to a stack overflow condition in the SNMP subsystem of the affected software. A successful exploit could allow a low-privileged attacker to cause the affected system to reload, resulting in a DoS condition, or allow a high-privileged attacker to execute arbitrary code as the root user and obtain full control of the affected system. Note: This vulnerability affects all versions of SNMP.

Affected and fixed versions

Exploitation

Severity

References

• CVE-2025-20352 on NVD
• CVE-2025-20352 in the CISA KEV catalog
• https://sec.cloudapps.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-snmp-x4LPhte (cited by CISA)
• https://sec.cloudapps.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-snmp-x4LPhte Mitigation, Vendor Advisory
• https://www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2025-20352 US Government Resource