CVE-2003-0543
Description
Integer overflow in OpenSSL 0.9.6 and 0.9.7 allows remote attackers to cause a denial of service (crash) via an SSL client certificate with certain ASN.1 tag values.
AI Insight
LLM-synthesized narrative grounded in this CVE's description and references.
Affected products
3cpe:2.3:a:openssl:openssl:0.9.6:*:*:*:*:*:*:*+ 2 more
- cpe:2.3:a:openssl:openssl:0.9.6:*:*:*:*:*:*:*
- cpe:2.3:a:openssl:openssl:0.9.7:*:*:*:*:*:*:*
- (no CPE)range: >=0.9.6, <=0.9.7
Patches
Vulnerability mechanics
Root cause
"An integer overflow occurs in OpenSSL's ASN.1 parsing when handling certain tag values in SSL client certificates."
Attack vector
A remote attacker can send a crafted SSL client certificate with specific ASN.1 tag values to an OpenSSL server. This malformed certificate triggers an integer overflow during the ASN.1 parsing process. The overflow can lead to a denial of service by crashing the server process [ref_id=1].
Affected code
The vulnerability lies within the ASN.1 parsing routines of OpenSSL versions prior to 0.9.6j and 0.9.7b. The provided exploit code demonstrates sending a corrupt client certificate to trigger the parsing bug [ref_id=1].
What the fix does
The advisory does not specify a patch or provide details on how the vulnerability is fixed. Remediation guidance suggests updating to OpenSSL versions 0.9.6j or 0.9.7b, or later, which are not affected by this issue.
Preconditions
- inputThe server must be configured to accept SSL client certificates.
- networkThe attacker must be able to send network traffic to the vulnerable server.
Reproduction
The provided reference [ref_id=1] includes a C program that can be used to reproduce the vulnerability by sending crafted client certificates to a target server.
Generated on Jun 2, 2026. Inputs: CWE entries + fix-commit diffs from this CVE's patches. Citations validated against bundle.
References
16- www.redhat.com/support/errata/RHSA-2003-291.htmlnvdPatchVendor Advisory
- bugzilla.redhat.com/bugzilla/show_bug.cginvdVendor Advisory
- www.cert.org/advisories/CA-2003-26.htmlnvdUS Government Resource
- www.kb.cert.org/vuls/id/255484nvdUS Government Resource
- secunia.com/advisories/22249nvd
- sunsolve.sun.com/search/document.donvd
- www-1.ibm.com/support/docview.wssnvd
- www.debian.org/security/2003/dsa-393nvd
- www.debian.org/security/2003/dsa-394nvd
- www.linuxsecurity.com/advisories/engarde_advisory-3693.htmlnvd
- www.redhat.com/support/errata/RHSA-2003-292.htmlnvd
- www.securityfocus.com/bid/8732nvd
- www.uniras.gov.uk/vuls/2003/006489/openssl.htmnvd
- www.vupen.com/english/advisories/2006/3900nvd
- oval.cisecurity.org/repository/search/definition/oval%3Aorg.mitre.oval%3Adef%3A4254nvd
- oval.cisecurity.org/repository/search/definition/oval%3Aorg.mitre.oval%3Adef%3A5292nvd
News mentions
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