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Memory LeakWeakness · CWE-401

CVE-2026-20012

HIGH · 8.6 CVSS v3.1 Published 2026-03-25
Mitigation only
No fix yet — a mitigation exists. There is no fixed release. A documented workaround reduces exposure in the meantime.
See remediation →
95/100
Remediation priority · Urgent
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) feature of Cisco IOS Software, Cisco IOS XE Software, Cisco Secure Firewall Adaptive Security Appliance (ASA) Software, and Cisco 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 on an affected device. This vulnerability is due to improper parsing of IKEv2 packets. An attacker could exploit this vulnerability by sending crafted IKEv2 packets to an affected device. A successful exploit of Cisco IOS Software and IOS XE Software could allow the attacker to cause the affected device to reload, resulting in a DoS condition. A successful exploit of Cisco Secure Firewall ASA Software and Secure FTD Software could allow the attacker to partially exhaust system memory, resulting in system instability, such as the inability 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 packet parser of Cisco IOS, IOS XE, ASA, and FTD software allows unauthenticated remote attackers to send crafted IKEv2 packets causing memory exhaustion. On IOS/IOS XE devices this triggers device reloads (DoS), while on ASA/FTD it causes progressive memory depletion preventing new IKEv2 VPN session establishment.

MitigationApply the relevant Cisco security patches for CVE-2026-20012 to all affected Cisco IOS, IOS XE, ASA, and FTD devices. Implement IKEv2 traffic rate limiting or ACLs as an interim compensating control if patches cannot be applied immediately.

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
High

CVSS:3.1/AV:N/AC:L/PR:N/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. Confirm IKEv2 is enabled on the device
    Run 'show crypto ikev2 sa' on IOS/IOS XE/ASA, or 'show vpn-sessiondb' on FTD to see if any IKEv2 security associations exist. Additionally, search the running configuration with 'show run | include crypto ikev2' for any IKEv2 policy or profile definitions.
    Affected if IKEv2 is configured or active SAs exist - the device processes IKEv2 traffic and is therefore exposed to the vulnerability.
  2. Identify the Cisco software platform and version
    Execute 'show version' on the device CLI. Note whether it runs IOS, IOS XE, ASA, or FTD software, and record the full version number displayed (e.g., 16.9.x, 9.x, etc.).
    Affected if The device runs any of the four affected platforms (IOS, IOS XE, ASA, FTD) and IKEv2 is enabled - you must compare your specific version against Cisco's published affected version list.
  3. Verify IKEv2 VPN tunnels are operational or configured
    Run 'show crypto ipsec sa' to check for active IPsec tunnels using IKEv2, and review 'show running-config | include crypto' to identify any IKEv2-specific tunnel configurations (ikev2, crypto ipsec profile, crypto isakmp policy with version 2).
    Affected if Active or configured IKEv2 VPN tunnels exist - the device is actively parsing IKEv2 packets and is vulnerable to the memory exhaustion flaw.
  4. Check device memory utilization baseline
    Run 'show memory summary' on IOS/IOS XE/ASA or 'show memory' on FTD to establish a baseline. Monitor for unusual increases in memory consumption over time if the device is receiving IKEv2 traffic.
    Affected if Memory usage shows abnormal growth without corresponding new sessions - this may indicate active exploitation of the memory leak vulnerability.

A device is affected if it runs Cisco IOS, IOS XE, ASA, or FTD software with IKEv2 enabled (configured or active), and the installed version falls within Cisco's published vulnerable version ranges for CVE-2026-20012.

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.

From vendor data
Mitigation available No clean upgrade yet — mitigate in the meantime
Mitigation

Apply the relevant Cisco security patches for CVE-2026-20012 to all affected Cisco IOS, IOS XE, ASA, and FTD devices. Implement IKEv2 traffic rate limiting or ACLs as an interim compensating control if patches cannot be applied immediately.

Have this fixed Scoped from the published advisory
  • Consultation6.0 h
  • Implementation8.0 h
  • Testing4.0 h
  • Review / QA3.0 h
21.0 hours of engineering $3,780
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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-2026-20012 in production — separate from our analysis above.

No notes yet

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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