CVE-2020-37191: Dialup Password Recovery DoS Vulnerability

CVE-2020-37191 Overview

CVE-2020-37191 is a denial of service vulnerability in Top Password Software Dialup Password Recovery version 1.30. The flaw stems from improper handling of oversized input in the application's registration dialog. A local attacker can crash the application by submitting a 5000-character payload into the User Name and Registration Code input fields. The vulnerability is classified under [CWE-120] (Buffer Copy without Checking Size of Input). Exploitation requires user interaction with the application interface and yields availability impact only. No confidentiality or integrity loss results from this issue.

Critical Impact
Local attackers can trigger an application crash in Dialup Password Recovery 1.30 by overflowing input fields with a 5000-character payload, causing loss of availability.

Affected Products

Top Password Software Dialup Password Recovery 1.30
Windows installations running the vulnerable build
Environments where the recovery utility is invoked interactively by end users

Discovery Timeline

2026-02-11 - CVE-2020-37191 published to NVD
2026-04-15 - Last updated in NVD database

Technical Details for CVE-2020-37191

Vulnerability Analysis

The vulnerability resides in the input handling routine of Dialup Password Recovery 1.30. The application allocates a fixed-size buffer for the registration dialog fields. When the supplied input exceeds the expected boundary, the application fails to validate the length before copying data. This results in an unhandled exception that terminates the process. The behavior is consistent with a classic boundary copy weakness tracked as [CWE-120]. Because exploitation requires local access and direct user interaction with the registration window, the attack surface remains limited. The result is a denial of service condition affecting the utility's availability rather than the host operating system.

Root Cause

The root cause is the absence of length validation on the User Name and Registration Code input fields. The application accepts inputs far beyond the size of its destination buffer. Memory corruption occurs at the point where the oversized string is processed, triggering a crash.

Attack Vector

An attacker with local access launches the application and opens the registration dialog. The attacker pastes a 5000-character string into the input fields. Submitting or processing this string forces the application to terminate. The attack vector is local with required user interaction, and it does not yield code execution or privilege escalation based on available references.

No verified exploit code is reproduced here. Technical details and the proof of concept are documented in Exploit-DB entry 47907 and the VulnCheck Advisory.

Detection Methods for CVE-2020-37191

Indicators of Compromise

Unexpected termination or crash logs associated with the Dialup Password Recovery executable
Windows Error Reporting events referencing the application's process name
Presence of unusually large clipboard or input strings near the time of an application crash

Detection Strategies

Monitor Windows Application event logs for repeated application faults tied to the vulnerable binary
Inspect endpoint telemetry for processes that crash immediately after receiving large input payloads
Correlate process exit events with user interaction on recovery utilities to surface abnormal input patterns

Monitoring Recommendations

Maintain inventory of hosts where Dialup Password Recovery 1.30 is installed
Alert on installation of unauthorized password recovery utilities on managed endpoints
Track application crash frequency to identify potential local abuse attempts

How to Mitigate CVE-2020-37191

Immediate Actions Required

Identify and inventory all endpoints running Dialup Password Recovery 1.30
Remove the application from systems where it is not required for legitimate operations
Restrict local user permissions to limit interactive use of unmanaged recovery tools

Patch Information

No vendor patch is referenced in the available advisories. Consult the Top Password Software website for any updated builds. Until a fixed release is published, removal or restriction remains the primary remediation. Additional context is available in the VulnCheck Advisory.

Workarounds

Uninstall Dialup Password Recovery 1.30 from production endpoints
Apply application allowlisting policies to block execution of the vulnerable binary
Limit input length on shared workstations through endpoint policy where feasible
Educate users to avoid pasting untrusted long strings into recovery utility fields

bash

# Configuration example: remove the vulnerable application via PowerShell
Get-WmiObject -Class Win32_Product | Where-Object { $_.Name -like "*Dialup Password Recovery*" } | ForEach-Object { $_.Uninstall() }