CVE-2018-16393

Vulnerability

A buffer overflow vulnerability exists in gemsafe_get_cert_len within libopensc/pkcs15-gemsafeV1.c in OpenSC before version 0.19.0-rc1 [1]. The flaw occurs when the application processes responses from a Gemsafe V1 Smartcard, leading to multiple buffer overflows without proper bounds checking [2].

Exploitation

An attacker must supply a crafted smartcard that sends malicious responses to APDU commands [2]. When the OpenSC library handles these responses, the lack of input validation triggers buffer overflows. The attacker does not need authentication, network access, or user interaction beyond presenting the malicious card to a system using OpenSC [2][4].

Impact

Successful exploitation can cause a denial of service (application crash) due to the buffer overflow [1]. The advisory notes possibly other unspecified impacts, but the primary consequence is a crash, leading to service interruption or loss of smartcard functionality [2].

Mitigation

OpenSC released version 0.19.0-rc1 on 2018-09-03, which fixes the vulnerability [4]. Users should upgrade to at least this version [1]. No workarounds are available for unpatched versions. The issue is not listed in CISA's Known Exploited Vulnerabilities catalog.