Vulnerability Note VU#524497

isakmpd crashes when handling ISAKMP packets with malformed "Delete Payload"

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:

    The Delete Payload contains a protocol-specific security association identifier that the sender has removed from its security association database and is, therefore, no longer valid. [...] It is possible to send multiple Security Parameter Index(es) (SPIs) in a Delete payload [...]

To this end, the format of the "Delete Payload" contains a "# of SPIs" field, specified as two octets. A flaw exists in the way that isakmpd handles malformed ISAKMP packets specifying an overly large number of SPIs for deletion. Such malformed packets could cause isakmpd to read out of bounds and crash.


A remote attacker could cause the isakmpd service to crash. 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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  • 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-2004-0221
  • 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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