CVE-2026-48131
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 · uneditedThe VPN service may mishandle an unexpected IKE fragment value received on the IKE port 500/UDP during the early stage of a connection attempt. This can cause the service to terminate unexpectedly, resulting in denial of service (temporary disruption of VPN-related functionality).
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 VPN service contains a denial-of-service vulnerability in its IKE (Internet Key Exchange) protocol handling on port 500/UDP. The service fails to properly handle unexpected IKE fragment values during the early stage of a connection attempt, causing an abrupt termination of the VPN service.
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
- High
- Privileges
- None
- User interaction
- None
- Scope
- Unchanged
- Confidentiality
- High
- Integrity
- High
- Availability
- High
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/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 running IKE daemon processesRun 'ps aux | grep -i ike' or 'ps aux | grep -i vpn' to list VPN-related processes. Also check for processes listening on UDP port 500 using 'netstat -ulnp | grep :500' or 'ss -ulnp | grep :500'.Affected if A VPN IKE daemon process is running and listening on UDP port 500.
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Verify UDP port 500 is exposedCheck if UDP port 500 is bound to a network interface accessible from external sources using 'nmap -sU -p 500 target' or by reviewing firewall rules with 'iptables -L -n' or 'ufw status verbose'.Affected if UDP port 500 is open and reachable from untrusted networks.
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Determine VPN software versionQuery the installed VPN package version using the system package manager (e.g., 'dpkg -l | grep -i vpn', 'rpm -qa | grep -i vpn', or check the vendor-specific binary version with 'vpn-daemon --version' or similar).Affected if The installed VPN software version falls within any known affected version range (compare to vendor advisories).
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Confirm IKE protocol support is enabledReview the VPN configuration files (typically in /etc/ipsec.d/, /etc/vpn/, or vendor-specific paths) and check for 'ike', 'phase1', or 'IKEv1/IKEv2' settings. Also verify the daemon is configured to accept incoming connections.Affected if IKE daemon is configured to accept incoming IKE connections on UDP port 500.
You are affected if a VPN IKE daemon is running with UDP port 500 exposed and the software version matches known vulnerable versions or is unpatched against this flaw.
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 vendor-provided patches for this vulnerability. If no patch is available, consider implementing network-level filtering or rate limiting on UDP port 500 to reduce exposure to malformed IKE packets while a fix is developed.
- Consultation6.0 h
- Implementation12.0 h
- Testing6.0 h
- Review / QA4.0 h
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Free · runs locallyCheck whether your project pulls in CVE-2026-48131 — 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-2026-48131 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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- Version or environment caveats, and links to real fixes
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