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Memory LeakWeakness · CWE-401

CVE-2025-20252

MEDIUM · 5.8 CVSS v3.1 Published 2025-08-14
Mitigation only
No fix yet — a mitigation exists. There is no fixed release. A documented workaround reduces exposure in the meantime.
See remediation →
67/100
Remediation priority · Elevated
Remotely reachable No privileges 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 Internet Key Exchange Version 2 (IKEv2) module of Cisco Secure Firewall Adaptive Security Appliance (ASA) Software and Secure Firewall Threat Defense (FTD) Software could allow an unauthenticated, remote attacker to trigger a memory leak, resulting in a denial of service (DoS) condition. This vulnerability is due to improper parsing of IKEv2 packets. An attacker could exploit this vulnerability by sending a continuous stream of crafted IKEv2 packets to an affected device. A successful exploit could allow the attacker to partially exhaust system memory, causing system instability like being unable to establish new IKEv2 VPN sessions. A manual reboot of the device is required to recover from this condition.

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

A memory leak vulnerability in the IKEv2 module of Cisco ASA and FTD software allows an unauthenticated remote attacker to send crafted IKEv2 packets that cause improper parsing and memory exhaustion. This prevents new IKEv2 VPN session establishment and requires a manual device reboot to recover.

MitigationApply the Cisco patch for this vulnerability and schedule a maintenance window to upgrade affected ASA/FTD devices; monitor memory utilization and consider rate-limiting IKEv2 connections as a temporary mitigation if patching is delayed.

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

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
None
User interaction
None
Scope
Changed
Confidentiality
None
Integrity
None
Availability
Low

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

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 device type and software
    Run 'show version' or 'show running-config' to confirm the device is Cisco ASA or FTD and note the software version number
    Affected if Device is Cisco ASA or FTD software and version is within the affected range (compare to Cisco advisory)
  2. Verify IKEv2 is enabled
    Run 'show vpn-sessiondb' or 'show crypto ipsec sa' to check for active IKEv2 VPN sessions; run 'show run crypto ikev2' to see IKEv2 configuration
    Affected if IKEv2 protocol is configured and actively used on the device
  3. Check current memory utilization
    Run 'show memory' or 'show memory detailed' to view available and used memory; monitor for abnormally high memory consumption
    Affected if Memory usage is unusually high or approaching exhaustion
  4. Review IKEv2 process status
    Run 'show process cpu history' and 'show process memory' to identify IKEv2-related processes consuming excessive resources
    Affected if IKEv2-related processes show abnormally high memory usage

The device is affected if it runs Cisco ASA or FTD with IKEv2 enabled and the installed version falls within the vulnerable version range published by Cisco, especially if experiencing high memory or failed VPN sessions.

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 the Cisco patch for this vulnerability and schedule a maintenance window to upgrade affected ASA/FTD devices; monitor memory utilization and consider rate-limiting IKEv2 connections as a temporary mitigation if patching is delayed.

Recommended fix Moderate confidence

Refer to Cisco advisory for version-specific fixed release (e.g., ASA 9.x or 10.x, FTD 7.x depending on your current version)

  1. Check Cisco Security Advisory (cisco-sa-ikev2-memleak) on sec.cloudapps.cisco.com for your specific ASA or FTD version and the corresponding fixed release
  2. Identify your exact ASA or FTD version using 'show version' command
  3. Upgrade to the fixed release indicated in the Cisco advisory for your product version
  4. After upgrade, verify the IKEv2 memory leak is resolved by monitoring memory usage under load
  5. Test that new IKEv2 VPN sessions can be established successfully
Caveat Review Cisco release notes for your target version for any configuration or behavioral changes before upgrading

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

Have this fixed Scoped from the published advisory
  • Consultation3.0 h
  • Implementation4.0 h
  • Testing3.0 h
  • Review / QA2.0 h
12.0 hours of engineering $2,130
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Scan for this in your stack

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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-2025-20252 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
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