CVE-2025-20222
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 · uneditedA vulnerability in the RADIUS proxy feature for the IPsec VPN feature of Cisco Secure Firewall Adaptive Security Appliance (ASA) Software and Cisco Secure Firewall Threat Defense (FTD) Software could allow an unauthenticated, remote attacker to cause a denial of service (DoS) condition. This vulnerability is due to improper processing of IPv6 packets. An attacker could exploit this vulnerability by sending IPv6 packets over an IPsec VPN connection to an affected device. A successful exploit could allow the attacker to trigger a reload of the device, resulting in a DoS 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 confidenceA vulnerability in the RADIUS proxy feature for IPsec VPN in Cisco ASA and FTD software allows unauthenticated remote attackers to trigger device reload by sending specially crafted IPv6 packets over an IPsec VPN connection. The improper processing of IPv6 packets leads to a denial-of-service condition requiring device reboot.
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 checksWork through these to decide whether this CVE applies to you.
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Identify the device typeConfirm whether the device is running Cisco ASA or Cisco FTD software using 'show version' or device documentationAffected if Device is not Cisco ASA or FTD (not affected)
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Check the software versionRun 'show version' on the ASA or FTD device to obtain the installed software version. Compare this version against the affected version ranges listed in the Cisco security advisory for CVE-2025-20222Affected if The installed version is not within the affected version ranges listed in the Cisco advisory
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Verify RADIUS proxy is configured for IPsec VPNUse 'show run | include radius' or examine the running configuration to check if RADIUS proxy is enabled for IPsec VPN connectionsAffected if RADIUS proxy for IPsec VPN is not enabled (the vulnerability requires this feature to be active)
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Confirm IPv6 traffic over IPsec VPNUse 'show crypto ipsec sa' or check active VPN session details to determine if IPv6 packets are being passed through established IPsec VPN tunnelsAffected if IPv6 traffic is not being forwarded over IPsec VPN tunnels (the trigger condition requires IPv6 packets over the VPN)
A device is affected if it is running a vulnerable version of Cisco ASA or FTD with RADIUS proxy for IPsec VPN enabled and IPv6 traffic actively passing through the IPsec VPN tunnel.
Generated from the published advisory. Verify against your own configuration.
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 dataApply the Cisco software update for this vulnerability. As an interim measure, consider disabling IPv6 on VPN interfaces if not required, or implement IPv6 traffic filtering at the perimeter until the patch can be deployed.
- Consultation3.0 h
- Implementation6.0 h
- Testing3.0 h
- Review / QA2.0 h
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Free · runs locallyCheck whether your project pulls in CVE-2025-20222 — or any other known-vulnerable package — straight from your lock files. Free and open source; it runs locally and uploads nothing.
References Go to the primary sourcePrimary sources — vendor advisories, patches and trackers. Where our summary and a reference disagree, the reference wins.
Primary sourcesPractitioner notes
ContributedPeer-ranked notes from engineers who’ve handled CVE-2025-20222 in production — separate from our analysis above.
The advisory tells you what broke. It rarely tells you what actually worked. If you’ve dealt with this one, that detail is what the next engineer is searching for.
- The version that genuinely resolved it — not the one the vendor claimed
- A config change or rule that shut the vector down
- A gotcha in the upgrade path that cost you an afternoon
No notes yet
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- Verified mitigations, workarounds, and config changes
- Version or environment caveats, and links to real fixes
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