CVE-2016-20041 in Screen Reader
Summary
by MITRE • 03/28/2026
Yasr 0.6.9-5 contains a buffer overflow vulnerability that allows local attackers to crash the application or execute arbitrary code by supplying an oversized argument to the -p parameter. Attackers can invoke yasr with a crafted payload containing junk data, shellcode, and a return address to overwrite the stack and trigger code execution.
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Analysis
by VulDB Data Team • 05/06/2026
The vulnerability identified as CVE-2016-20041 resides within the Yasr application version 0.6.9-5, representing a critical buffer overflow flaw that presents significant security risks to systems utilizing this software. This issue manifests when the application processes command-line arguments, specifically the -p parameter, which serves as an entry point for malicious input manipulation. The buffer overflow vulnerability stems from inadequate input validation and bounds checking within the application's argument parsing mechanism, creating an exploitable condition that can be leveraged by local attackers with system-level access.
The technical exploitation of this vulnerability occurs through careful crafting of the -p parameter with oversized input data that exceeds the allocated buffer space. When Yasr processes this malformed argument, the excessive data overflows into adjacent memory regions, potentially corrupting the stack structure and overwriting critical program execution elements including return addresses and function pointers. This memory corruption enables attackers to redirect program execution flow by injecting malicious shellcode into the overflowed buffer space, effectively allowing for arbitrary code execution with the privileges of the running process. The vulnerability specifically targets the stack-based buffer overflow pattern, which aligns with CWE-121, a well-documented weakness category for stack-based buffer overflow conditions.
From an operational perspective, this vulnerability presents a severe threat to system integrity and availability as local attackers can leverage it to either crash the application through controlled memory corruption or achieve persistent code execution within the target environment. The impact extends beyond simple application instability since successful exploitation can provide attackers with elevated privileges and potentially serve as a foothold for further system compromise. The vulnerability's local nature means that attackers must already have access to the system to exploit it, but this requirement does not diminish its severity as it can be combined with other local privilege escalation techniques to achieve more significant compromises.
The attack vector for this vulnerability involves invoking the Yasr application with a specially crafted argument that includes junk data, shellcode, and a carefully calculated return address designed to overwrite the stack and redirect program execution. This exploitation technique follows standard buffer overflow methodologies and can be categorized under the ATT&CK framework's T1059.007 command and scripting interpreter for execution, as well as T1068 local privilege escalation techniques. The vulnerability's presence in the command-line argument processing highlights the importance of proper input validation and secure coding practices in application development.
Mitigation strategies for CVE-2016-20041 should prioritize immediate patching of the Yasr application to version 0.6.9-6 or later, which contains the necessary fixes for the buffer overflow condition. System administrators should implement strict input validation measures to prevent malformed arguments from reaching the vulnerable code paths, while also considering the application of address space layout randomization and stack canaries to make exploitation more difficult. Additionally, monitoring for unusual command-line argument patterns and implementing principle of least privilege access controls can help reduce the attack surface and limit potential damage from successful exploitation attempts. Organizations should also conduct thorough code reviews of similar applications to identify and remediate comparable buffer overflow vulnerabilities within their software infrastructure.