CVE-2025-20352 Cisco IOS and IOS XE: memory-safety flaw
In plain words: The program mishandles the memory it uses to keep track of data. A specially made input can scramble that memory. Usually lets an attacker crash the program or run their own code with its permissions.
Confirmed exploited by CISA on · US federal patch deadline Oct 20, 2025
What to do
- Install Cisco's security update for IOS and IOS XE. If no update exists, follow the vendor's workaround or stop using the product until one ships.
- Install system updates the day they come out — most phone zero-days are fixed in a point release.
- Restart your phone every few days; some spyware does not survive a reboot.
- If you are a journalist, activist, lawyer, politician or executive, turn on Lockdown Mode (iPhone) or Advanced Protection (Android).
Who is affected
Could reach you. This one is aimed at devices or apps of the kind people own.
What's at risk: Messages, photos, location, microphone and camera. The most serious ones are "zero-click": no tap needed from the owner. They are usually used as spyware against a small number of chosen people.
The details
- Official name
- Cisco IOS and IOS XE Software SNMP Denial of Service and Remote Code Execution Vulnerability
- Product
- Cisco IOS and IOS XE
- CISA description
- 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.
- Type of flaw
- Memory-safety flaw (CWE-121)
- Confirmed exploited
- Sep 29, 2025
- US federal patch deadline
- Oct 20, 2025
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Answering about CVE-2025-20352 ·
Questions about CVE-2025-20352
Is CVE-2025-20352 being exploited?
Yes. CISA added CVE-2025-20352 to its Known Exploited Vulnerabilities catalog on Sep 29, 2025, which means there is reliable evidence of real-world attacks.
How do I fix CVE-2025-20352?
Install Cisco's security update for IOS and IOS XE. If no update exists, follow the vendor's workaround or stop using the product until one ships. Install system updates the day they come out — most phone zero-days are fixed in a point release.
Am I affected by CVE-2025-20352?
Only if you use Cisco IOS and IOS XE. This one is aimed at devices or apps of the kind people own.