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Actively exploited in the wild. This CVE is on the CISA Known Exploited Vulnerabilities list — treat remediation as urgent. Federal remediation due by 20 Oct 2025.
Ios Xe Sd WanOperating system · Cisco

CVE-2025-20352

HIGH · 7.7 CVSS v3.1 Published 2025-09-24
Mitigation only
No fix yet — a mitigation exists. There is no fixed release. A documented workaround reduces exposure in the meantime.
See remediation →
100/100
Remediation priority · Urgent
In the wild Remotely reachable Zero-click

Official description Straight from the sourceThe vendor's or NVD's own wording, published unedited. Authoritative, but often terse — it says what broke, rarely what to do.

NVD · unedited
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.

Technical summary Written by usOur analysis, written from the advisory, the CVSS vector and the affected-version data. It adds context the advisory leaves out, and never invents facts that are not in the source.

dbcve analysis · high confidence

Stack overflow vulnerability in Cisco IOS/IOS XE SNMP subsystem allows authenticated attackers to send crafted SNMP packets that can cause DoS (device reload) via low-privilege access or arbitrary code execution as root via high-privilege access.

MitigationApply Cisco IOS/IOS XE software updates when available; as interim measures, restrict SNMP access to trusted management networks via ACLs, disable SNMPv1/v2c, or use SNMPv3 with strong authentication/encryption.

Verify against the referenced sources before acting — the references below are authoritative for this CVE, this summary is not.

Affected products & versions What the vendor confirmedThe version ranges the vendor confirmed as vulnerable. If your version sits inside a range here, treat yourself as exposed until you have upgraded.

NVD · CPE data
Ios Xe Sd WanOperating system
Affected:= 16.9.1= 16.9.2= 16.9.3= 16.9.4= 16.10.1= 16.10.2= 16.10.3= 16.10.3a= 16.10.3b= 16.10.4= 16.10.5= 16.10.6
Ios XeOperating system
Affected:= 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
iOSOperating system
Affected:= 12.2\(33\)sxi= 12.2\(33\)sxi1= 12.2\(33\)sxi2= 12.2\(33\)sxi2a= 12.2\(33\)sxi3= 12.2\(33\)sxi4= 12.2\(33\)sxi4a= 12.2\(33\)sxi5= 12.2\(33\)sxi6= 12.2\(33\)sxi7= 12.2\(33\)sxi8= 12.2\(33\)sxi8a

CVSS breakdown How the score is builtThe industry scoring standard. It rates how the flaw is reached, what it takes to exploit, and what an attacker gains — the score is derived from those, not the other way round.

From the vector
Attack vector
Network
Complexity
Low
Privileges
Low
User interaction
None
Scope
Changed
Confidentiality
None
Integrity
None
Availability
High

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

Am I affected? How to checkSteps we derive from the advisory and the affected-version data, so you can decide whether this CVE reaches your setup. They are a guide, not a scan — your own configuration is the authority.

dbcve checks

Work through these to decide whether this CVE applies to you.

  1. Identify the Cisco software version
    Run 'show version' on the device CLI and locate the version string (e.g., 16.9.4, 3.5.3e, 12.2(33)sxi5)
    Affected if The displayed version matches one listed in the affected versions for Cisco IOS Xe SD WAN, Cisco IOS XE, or Cisco iOS
  2. Verify SNMP is enabled
    Run 'show snmp' and look for SNMP engine status and community string entries
    Affected if SNMP is enabled and an SNMP engine is listed as running, indicating the SNMP subsystem is active
  3. Check SNMP configuration for vulnerable setup
    Run 'show running-config | include snmp' to view SNMP community strings and user configurations
    Affected if SNMPv2c community strings are configured (simpler to exploit) or SNMPv3 users without encryption are in use
  4. Confirm IPv4/IPv6 SNMP access is possible
    Review access lists (ACLs) applied to SNMP with 'show ip access-lists' or check if SNMP listens on any interface
    Affected if SNMP is accessible from any network segment where an attacker could send packets (not restricted to management-only networks)

A device is affected if it runs a matching affected iOS/iOS XE version AND has SNMP enabled with a community string or SNMPv3 user that an attacker could use for authentication.

Generated from the published advisory. Verify against your own configuration.

Check your environment

Paste your version and any relevant configuration and it will be compared against the affected criteria above. Do not include secrets or credentials.

AI-assisted, checked against the advisory. Informational, not a guarantee.

Remediation Closing itWhat it takes to close this. Where a vendor fix exists we point at it; where none exists we say so plainly, and can build one. Effort estimates are scoped from the advisory, not from your codebase.

dbcve · scoped
Mitigation available No clean upgrade yet — mitigate in the meantime
Mitigation

Apply Cisco IOS/IOS XE software updates when available; as interim measures, restrict SNMP access to trusted management networks via ACLs, disable SNMPv1/v2c, or use SNMPv3 with strong authentication/encryption.

Recommended fix Moderate confidence

Refer to Cisco Security Advisory for CVE-2025-20352 - fixed releases vary by product family and are listed in the official advisory

  1. 1. Identify the exact Cisco IOS or IOS XE version currently running on the device using 'show version' command.
  2. 2. Consult the official Cisco Security Advisory for CVE-2025-20352 at sec.cloudapps.cisco.com to obtain the specific fixed releases for your product line.
  3. 3. Review the Cisco SNMP Best Practices documentation to understand current SNMP configuration and disable SNMPv1/v2c if not required.
  4. 4. If upgrading immediately is not feasible, consider restricting SNMP access via ACLs on the device: configure an access-list to limit SNMP source IPs, then apply it using 'snmp-server community <string> ro <acl-number>' or 'snmp-server group <group> v3 auth access <acl-number>'.
  5. 5. Apply the vendor-recommended upgrade during a planned maintenance window following standard Cisco IOS upgrade procedures.
  6. 6. After upgrading, verify the SNMP subsystem functions correctly and monitor for any anomalies.
Caveat Review Cisco release notes for your target version for any feature changes or migration considerations before upgrading

Generated from the published advisory — verify against the referenced sources before acting.

Fix this in Ios Xe Sd Wan Exploited in the wild — priority engagement
  • Consultation4.0 h
  • Implementation8.0 h
  • Testing4.0 h
  • Review / QA2.0 h
18.0 hours of engineering $3,200
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References Go to the primary sourcePrimary sources — vendor advisories, patches and trackers. Where our summary and a reference disagree, the reference wins.

Primary sources

Practitioner notes

Contributed

Peer-ranked notes from engineers who’ve handled CVE-2025-20352 in production — separate from our analysis above.

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What this is

A place for practitioners to share what actually worked: a mitigation you’ve tested, a configuration change, a version- or environment-specific caveat, or a link to a verified patch. The most useful notes rise to the top as peers upvote them, so the signal stays high.

What belongs here
  • Verified mitigations, workarounds, and config changes
  • Version or environment caveats, and links to real fixes
  • No weaponised exploit code, or anything meant to cause harm
  • No spam, self-promotion, credentials, or personal data