Vulnerability Note VU#349113

isakmpd fails to handle ISAKMP packets with "Payload Length" of zero

Original Release date: 27 Aug 2004 | Last revised: 27 Aug 2004


A vulnerability exists in the isakmpd that could allow a remote attacker to cause a denial of service.


The OpenBSD isakmpd establishes security associations for encrypted and authenticated (IPsec) network traffic. It implements the Internet Security Association and Key Management Protocol (ISAKMP) and Internet Key Exchange (IKE) protocol. The ISAKMP standard specifies a "Payload Length" field within the "Generic Payload Header". This field is populated by the sender and specifies the length in octets of the current payload, including the generic payload header. A flaw in the handling of packets with a specified length of zero could cause isakmpd to enter an infinite loop, preempting normal operations.

This issue is reportedly similar to VU#738518.


A remote attacker could cause the isakmpd service to become unresponsive. Subsequent IPsec-enabled communications may be disrupted as a result.


Apply a patch from the vendor

Patches have been released to address this issue. Please see the Systems Affected section of this document for more details.

Systems Affected (Learn More)

VendorStatusDate NotifiedDate Updated
OpenBSDAffected-20 Aug 2004
If you are a vendor and your product is affected, let us know.

CVSS Metrics (Learn More)

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Temporal N/A N/A
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  • None


This vulnerability was discovered by Rapid7 using their Striker test suite.

This document was written by Chad R Dougherty based on information published in Rapid7 Advisory R7-0018 .

Other Information

  • CVE IDs: CAN-2004-0218
  • Date Public: 19 Mar 2004
  • Date First Published: 27 Aug 2004
  • Date Last Updated: 27 Aug 2004
  • Severity Metric: 1.69
  • Document Revision: 10


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