Vulnerability Note VU#748355

ASN.1 parsing errors exist in implementations of SSL, TLS, S/MIME, PKCS#7 routines

Original Release date: 30 Jul 2002 | Last revised: 30 Sep 2002


Abstract Syntax Notation number One (ASN.1) is an international standard used to describe and transmit data packets between applications and across networks. There is a vulnerability related to ASN.1 that could permit an attacker to cause a denial of service or potentially execute arbitrary code.


The ASN.1 library used by OpenSSL has several parsing errors which allow malformed certificate encodings to be parsed incorrectly. Attackers can exploit this vulnerability remotely to cause a denial of service or potentially execute arbitrary code, depending on the circumstance under which the vulnerable parser is exercised. Routines affected include those supporting SSL and TLS applications, as well as S/MIME (PKCS#7) and certificate creation.

Specifically, the parser implemented in various ASN.1 libraries accepts certain invalidly encoded data (in this case with an invalid length parameter) leading to improper interpretation of the data. This leads to undefined behavior which may lead to other security-related impacts (data executed as code, service termination, disclosure of sensitive information).


Attackers can exploit this vulnerability remotely to cause a variety of impacts, including denial of service, arbitrary code execution, and disclosure of sensitive information.


Apply the patches made available by your vendor, or upgrade to the recommended version. The "Systems Affected" section contains a list of vendors and details about the status of their products. Clicking on the vendor name will provide you with any statements that the vendor has made.

The OpenSSL team has recently released OpenSSL 0.9.6g to completely remove all known instances of this vulnerability.

Systems Affected (Learn More)

VendorStatusDate NotifiedDate Updated
Apple Computer Inc.Affected29 Jul 200209 Aug 2002
DebianAffected29 Jul 200209 Aug 2002
Guardian DigitalAffected29 Jul 200209 Aug 2002
Hewlett-Packard CompanyAffected29 Jul 200209 Aug 2002
IBMAffected29 Jul 200209 Aug 2002
ISCAffected-09 Aug 2002
Juniper NetworksAffected29 Jul 200216 Aug 2002
MandrakeSoftAffected-23 Sep 2002
NetBSDAffected29 Jul 200223 Sep 2002
OpenLDAPAffected29 Jul 200209 Aug 2002
OpenPKGAffected-09 Aug 2002
OpenSSLAffected22 Jul 200209 Aug 2002
OracleAffected29 Jul 200210 Aug 2002
Red Hat Inc.Affected29 Jul 200209 Aug 2002
Secure Computing CorporationAffected-30 Sep 2002
If you are a vendor and your product is affected, let us know.View More »

CVSS Metrics (Learn More)

Group Score Vector
Base N/A N/A
Temporal N/A N/A
Environmental N/A N/A



This vulnerability was independently discovered by Adi Stav and James Yonan. Our thanks to Stephen Henson for reporting on this vulnerability.

This document was written by Jason A Rafail and Jeffrey S. Havrilla.

Other Information

  • CVE IDs: CAN-2002-0659
  • CERT Advisory: CA-2002-23
  • Date Public: 30 Jul 2002
  • Date First Published: 30 Jul 2002
  • Date Last Updated: 30 Sep 2002
  • Severity Metric: 31.33
  • Document Revision: 32


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