CVE-2017-17818

Vulnerability

A heap-based buffer over-read vulnerability exists in Netwide Assembler (NASM) version 2.14rc0, specifically in the paste_tokens function within asm/preproc.c. The issue occurs in a while loop that does not properly check bounds, leading to an out-of-bounds read. Affected versions include NASM 2.14rc0; earlier versions may also be vulnerable as per the advisory [1].

Exploitation

An attacker can exploit this vulnerability by providing a specially crafted source file to be processed by NASM. The user or automated system must open this file, triggering the heap-based buffer over-read. No authentication or special network position is required beyond delivering the malicious file.

Impact

Successful exploitation causes NASM to crash, resulting in a denial of service. The Ubuntu security notice also suggests that arbitrary code execution may be possible, though the CVE description primarily highlights denial of service [1]. The attacker could potentially execute arbitrary code in the context of the NASM process.

Mitigation

Ubuntu has released a fix in version 2.11.06-1ubuntu0.1 for Ubuntu 14.04 LTS. Users should update their NASM packages via standard system update procedures. No workarounds have been published; updating to the patched version is recommended [1].