# What is CVE-2025-20352?

> CVE-2025-20352 is a high-severity flaw (CVSS 7.7) in IOS XE from Cisco, published on 24 September 2025. It is on the list of flaws known to be exploited, so criminals are already using it. The latest forecast puts its chance of use in the next 30 days at 40%. If you run an affected version, patch it first.

Canonical page: https://www.precursorintelligence.com/what-is/cve-2025-20352

## At a glance

- **Verdict:** Fix this now. Attackers are using this flaw today. If you run an affected version, it goes to the top of your list.
- **Precursor Intelligence risk score:** 81 out of 100 (High); action: Emergency patch. Kept up to date as the evidence changes.
- **Severity:** High (CVSS 7.7 out of 10)
- **Known to be exploited:** Yes, it is on the government list of flaws known to be exploited
- **Chance of use in the next 30 days:** 40% (latest exploit-likelihood forecast)
- **Published:** 24 September 2025
- **Record last updated:** 28 October 2025
- **Main product:** IOS XE from Cisco
- **Affected products:** 3

## What is CVE-2025-20352? In plain terms

It can be attacked from anywhere on the internet with an ordinary user account, and nobody has to click anything. If it works, the attacker can take it offline.

### The official 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.

### What kind of flaw is it?

- CWE-121: Stack-based Buffer Overflow

### How an attack on it works

- Where an attacker can be: Anywhere on the internet
- How hard it is to pull off: Easy: no special conditions
- Login needed first: An ordinary user account
- Does someone have to click: No, nobody has to do anything
- What an attacker gets: Can take it offline

Severity vector: `CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:N/I:N/A:H`

## Is CVE-2025-20352 being exploited? Yes

Attackers are already using it. It is on the government list of flaws known to be exploited, and the latest forecast puts the chance of it being used in the next 30 days at 40%.

Exploit likelihood over the last 7 days: 39%, 39%, 39%, 40%, 40%, 40%, 40%.

### Timeline

- 24 September 2025: Published
- 30 September 2025: Added to the known-exploited list
- 28 October 2025: Record last updated
- 16 June 2026: Exploit likelihood jumped

### How Precursor Intelligence ranks it

CVE-2025-20352 scores **81 out of 100 (High)**, with the action "Emergency patch".

Every published flaw gets a risk score from 0 to 100, kept up to date as the evidence changes. Four things go into the score, from the one that counts most to the ones that count less:

- Evidence it is being exploited: biggest factor
- How severe it is: strong factor
- How widely exposed it is: smaller factor
- Threat activity around it: smaller factor

85 and above is Critical. Anything confirmed as exploited is always marked for an emergency patch, whatever its score. When this flaw matches software you track, it lands in your list with its score and the reasons behind it.

## Who is affected by CVE-2025-20352?

The published record lists 3 products.

- [IOS XE](https://www.precursorintelligence.com/product/cisco/ios_xe) by [Cisco](https://www.precursorintelligence.com/vendors/cisco) (Operating system): 3.5.0e, 3.5.0sq, 3.5.1e, 3.5.1sq, 3.5.2e, 3.5.2sq, 3.5.3e, 3.5.3sq, 3.5.4sq, 3.5.5sq, 3.5.6sq, 3.5.7sq, 3.5.8sq, 3.6.0e, 3.6.1e, 3.6.2ae, 3.6.2e, 3.6.3e, 3.6.4e, 3.6.5ae, 3.6.5e, 3.6.6e, 3.6.7be, 3.6.7e, 3.6.8e, 3.6.9e, 3.6.10e, 3.7.0e, 3.7.1e, 3.7.2e, 3.7.3e, 3.7.4e, 3.7.5e, 3.8.0e, 3.8.1e, 3.8.2e, 3.8.3e, 3.8.4e, 3.8.5ae, 3.8.5e and 309 more
- [IOS](https://www.precursorintelligence.com/product/cisco/ios) by [Cisco](https://www.precursorintelligence.com/vendors/cisco) (Operating system): 12.2(33)sxi, 12.2(33)sxi1, 12.2(33)sxi2a, 12.2(33)sxi2, 12.2(33)sxi3, 12.2(33)sxi4a, 12.2(33)sxi4, 12.2(33)sxi5, 12.2(33)sxi6, 12.2(33)sxi7, 12.2(33)sxi8a, 12.2(33)sxi8, 12.2(33)sxi9, 12.2(33)sxi10, 12.2(33)sxi11, 12.2(33)sxi12, 12.2(33)sxi13, 12.2(33)sxi14, 12.2(33)sxj, 12.2(33)sxj1, 12.2(33)sxj2, 12.2(33)sxj3, 12.2(33)sxj4, 12.2(33)sxj5, 12.2(33)sxj6, 12.2(33)sxj7, 12.2(33)sxj8, 12.2(33)sxj9, 12.2(33)sxj10, 12.2(50)sq, 12.2(50)sq1, 12.2(50)sq2, 12.2(50)sq3, 12.2(50)sq4, 12.2(50)sq5, 12.2(50)sq6, 12.2(50)sq7, 12.2(53)ez, 12.2(55)ez, 12.2(55)se and 686 more
- [Ios XE SD-WAN](https://www.precursorintelligence.com/product/cisco/ios_xe_sd-wan) by [Cisco](https://www.precursorintelligence.com/vendors/cisco) (Operating system): 16.9.1, 16.9.2, 16.9.3, 16.9.4, 16.10.1, 16.10.2, 16.10.3a, 16.10.3b, 16.10.3, 16.10.4, 16.10.5, 16.10.6, 16.11.1a, 16.12.1b, 16.12.1d, 16.12.1e, 16.12.2r, 16.12.3, 16.12.4a, 16.12.4, 16.12.5

## How do I fix CVE-2025-20352?

1. **Check whether you run it.** Compare your versions with the affected products above. Not sure what you run? Precursor Intelligence can work it out from your public website, or you can pick it from a list.
2. **Apply the vendor’s fix.** Install the update named in the vendor’s advisory. We’ve put the advisory first in the list.
3. **If you can’t patch today.** Follow any mitigation the vendor publishes, and limit who can reach the affected system from the internet until the update is in.
4. **Check it wasn’t used before you patched.** Because criminals are already using this flaw, look for signs of a break-in on affected systems using the vendor’s guidance.

### References

- [sec.cloudapps.cisco.com](https://sec.cloudapps.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-snmp-x4LPhte) (Mitigation, Vendor advisory)
- [cisa.gov](https://www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2025-20352) (Government resource)

## Questions

### What is CVE-2025-20352?

CVE-2025-20352 is a high-severity flaw in IOS XE from Cisco, published on 24 September 2025. It can be attacked from anywhere on the internet with an ordinary user account, and nobody has to click anything. If it works, the attacker can take it offline.

### How serious is CVE-2025-20352?

It scores 7.7 out of 10 on the CVSS severity scale, which is high. Our risk score for CVE-2025-20352 is 81 out of 100, which is High. Its action is "Emergency patch". Attackers are using this flaw today. If you run an affected version, it goes to the top of your list.

### Is CVE-2025-20352 being exploited?

Attackers are already using it. It is on the government list of flaws known to be exploited, and the latest forecast puts the chance of it being used in the next 30 days at 40%.

### Which versions does CVE-2025-20352 affect?

For IOS XE from Cisco: 3.5.0e, 3.5.0sq, 3.5.1e, 3.5.1sq, 3.5.2e, 3.5.2sq and 343 more. The record lists 3 products in all, each with its versions, under "Who is affected" on this page.

### How do I fix CVE-2025-20352?

Install the update the vendor names in its advisory, linked first under "How do I fix" on this page. If you can't patch today, follow the vendor's mitigation and limit who can reach the affected system from the internet. Because criminals are already using it, also check affected systems for signs of a break-in.

## Does CVE-2025-20352 affect you?

Precursor Intelligence keeps checking for you:

- **Tell us what you run.** Pick your software from a list, or let us work it out from your website.
- **We match it to every flaw.** Over 400,000 published flaws, checked against your list.
- **Ranked by real-world risk.** Every flaw gets a 0 to 100 risk score, kept up to date, led by evidence criminals are using it.
- **Told as soon as we know.** An alert by email, in the app or by webhook to your own tools.

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