CVE-2021-1424
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 ipsecmgr process of Cisco ASR 5000 Series Software (StarOS) could allow an unauthenticated, remote attacker to cause a denial of service (DoS) condition. This vulnerability is due to insufficient validation of incoming Internet Key Exchange Version 2 (IKEv2) packets. An attacker could exploit this vulnerability by sending specifically malformed IKEv2 packets to an affected device. A successful exploit could allow the attacker to cause the ipsecmgr process to restart, which would disrupt ongoing IKE negotiations and result in a temporary DoS condition.Cisco has released software updates that address this vulnerability. There are no workarounds that address this vulnerability.
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 confidenceThe ipsecmgr process in Cisco ASR 5000 Series routers running StarOS lacks sufficient validation of incoming IKEv2 packets. An attacker can exploit this by sending malformed IKEv2 packets to trigger a process restart, causing a denial of service through disruption of IKE negotiations.
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
- Unchanged
- Confidentiality
- None
- Integrity
- None
- Availability
- Low
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/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 checksWork through these to decide whether this CVE applies to you.
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Confirm hardware platform is Cisco ASR 5000 SeriesRun 'show hardware' or 'show chassis' command to verify the device modelAffected if Device is not a Cisco ASR 5000 Series router - vulnerability does not apply
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Confirm StarOS is the running softwareRun 'show software' or check the boot flash for StarOS imageAffected if Device does not run StarOS - vulnerability does not apply
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Identify StarOS versionRun 'show version' or 'show software version' to display the installed StarOS releaseAffected if Version is within the affected range and no patch has been applied
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Verify IKEv2/ipsecmgr is enabledRun 'show ipsec ike' or 'show ipsecmgr status' to check if IKEv2 negotiation and ipsecmgr process are activeAffected if IKEv2 and ipsecmgr are not enabled - the vulnerable code path is not reachable
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Check for ipsecmgr process restarts or crashesRun 'show process ipsecmgr' or review system logs for ipsecmgr process restart eventsAffected if Recent ipsecmgr restarts correlate with malformed IKEv2 traffic
User is affected if they run a Cisco ASR 5000 Series router with StarOS that has IKEv2/ipsecmgr enabled and the installed version falls within the vulnerable range before Cisco applied the fix.
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 that addresses this vulnerability; no workarounds are available.
- Consultation4.0 h
- Implementation4.0 h
- Testing2.0 h
- Review / QA2.0 h
An estimate, not a bill — we confirm scope with you before any work starts. Need it this week? Rush from $3,488.
Scan for this in your stack
Free · runs locallyCheck whether your project pulls in CVE-2021-1424 — 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-2021-1424 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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