CVE-2019-6502

Vulnerability

A memory leak exists in sc_context_create in ctx.c of libopensc in OpenSC version 0.19.0. The leak manifests when the eidenv tool calls this function, as reported in [1]. The allocated memory via calloc at line 809 and subsequent allocations (e.g., from pcsc_init, list_init, and strdup) are not freed before the context is discarded, leading to direct and indirect leaks.

Exploitation

An attacker does not require special network access or authentication; the vulnerability is triggered locally by running the eidenv tool [1]. The sequence involves simply invoking eidenv, which calls sc_context_create in ctx.c at line 809, resulting in unreleased heap memory.

Impact

An attacker who can execute the eidenv binary can cause a memory leak, potentially exhausting system memory over repeated invocations. This constitutes a denial-of-service (DoS) impact by degrading system availability. There is no confidentiality or integrity impact.

Mitigation

The vulnerability is addressed in OpenSC 0.20.0, released on 29 December 2019 [2]. Users should upgrade to this version or later. No workarounds are documented for unpatched versions.