CVE-2025-20352: Cisco IOS and IOS XE stack overflow in SNMP subsystem

CVE-2025-20352 · Severity: critical · CVSS 7.7 · Exploited in the wild · Published 2025-09-29

A vulnerability exists in the networking software used by many Cisco routers and switches to manage device health and performance. An attacker with valid management credentials could send a malicious message that causes the device to crash and restart, or in some cases, take full control of the system. This could lead to significant network outages or unauthorized access to sensitive corporate traffic.

Technologies: Cisco IOS, Cisco IOS XE, Cisco IOS XR. Vendors: Cisco.

Quick answers

Is CVE-2025-20352 exploited in the wild?
Yes. CVE-2025-20352 is known to be exploited in the wild, first recorded on 29 September 2025. Treat it as urgent.
How severe is CVE-2025-20352?
Critical severity, with a CVSS score of 7.7, published 29 September 2025.
Which products and versions are affected?
Cisco IOS All versions of SNMP subsystem; Cisco IOS XE All versions of SNMP subsystem; Cisco IOS XE SD-WAN 16.9.1, 16.9.2, 16.9.3, 16.9.4.
Is there a fix for CVE-2025-20352?
No fixed version is recorded yet. Check the vendor's advisory in the references below. If you run it, Junglewise drafts a mitigation that fits your setup and applies it once you approve, with senior security engineers behind it.
How is CVE-2025-20352 attacked?
It is attacked over the network, in an operating system.
Am I affected by CVE-2025-20352?
Check whether you run Cisco IOS, Cisco IOS XE, Cisco IOS XE SD-WAN or one of the others listed at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

Technical details

A stack-based buffer overflow (CWE-121) exists in the Simple Network Management Protocol (SNMP) subsystem of Cisco IOS and IOS XE Software. The vulnerability is triggered by sending a specially crafted SNMP packet over IPv4 or IPv6 to an affected device. Exploitation requires authentication: low-privileged attackers with read-only community strings or SNMPv3 credentials can trigger a system reload (DoS), while high-privileged attackers (Privilege 15) can achieve remote code execution as the root user. This vulnerability has been reported as exploited in the wild.

Affected products

  • Cisco IOS All versions of SNMP subsystem
  • Cisco IOS XE All versions of SNMP subsystem
  • Cisco IOS XE SD-WAN 16.9.1, 16.9.2, 16.9.3, 16.9.4

Timeline

  • 2025-09-29: advisory: Initial disclosure by Cisco and NVD
  • 2025-09-29: kev added: Added to CISA Known Exploited Vulnerabilities catalog

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