CVE-2025-20253
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 IKEv2 feature of Cisco IOS Software, IOS XE Software, Secure Firewall ASA Software, and Secure FTD Software could allow an unauthenticated, remote attacker to cause the device to reload, resulting in a DoS condition. This vulnerability is due to the improper processing of IKEv2 packets. An attacker could exploit this vulnerability by sending crafted IKEv2 packets to an affected device. A successful exploit could allow the attacker to cause an infinite loop that exhausts resources and could cause the device to reload.
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 · moderate confidenceA vulnerability in the IKEv2 feature of Cisco IOS Software, IOS XE Software, Secure Firewall ASA Software, and Secure FTD Software allows an unauthenticated remote attacker to send crafted IKEv2 packets that trigger an infinite loop, exhausting device resources and causing the device to reload (DoS).
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 Cisco product and software versionExecute 'show version' or 'show version | include (IOS|IOS XE|ASA|FTD)' to determine the exact software version and platform typeAffected if The device runs Cisco IOS Software, IOS XE Software, Secure Firewall ASA Software, or Secure FTD Software without the applicable security patches
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Verify IKEv2 is enabled on the deviceRun 'show running-config | include ikev2' or check for IKEv2-related configuration such as 'crypto ikev2', 'ikev2 profile', or 'crypto map' entries referencing IKEv2Affected if IKEv2 configuration exists in the running config, meaning the feature is active
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Confirm IKEv2 is listening on external interfacesUse 'show crypto ikev2 sa' or 'show crypto ipsec sa' to check for active IKEv2 security associations, and verify interface configurations with 'show ip interface' to see if IKEv2-facing interfaces are externally accessibleAffected if The device has active IKEv2 security associations or IKEv2 is configured on interfaces reachable from untrusted networks
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Cross-reference the installed version with affected releasesCompare the output from 'show version' against Cisco's official security advisory for CVE-2025-20253 to determine if the specific version falls within affected release trainsAffected if The running software version is among the unpatched versions listed as affected in the Cisco security advisory
The device is affected if it runs vulnerable Cisco IOS, IOS XE, ASA, or FTD software AND has IKEv2 enabled and exposed to untrusted networks.
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 Cisco security patches when available. If immediate patching is not feasible, consider disabling IKEv2 on affected devices or implementing network-level filtering to restrict IKEv2 traffic to trusted sources at the perimeter.
- Consultation6.0 h
- Implementation12.0 h
- Testing8.0 h
- Review / QA4.0 h
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Scan for this in your stack
Free · runs locallyCheck whether your project pulls in CVE-2025-20253 — 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-2025-20253 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
- No weaponised exploit code, or anything meant to cause harm
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