CVE-2018-25426: WinMTR Buffer Overflow Vulnerability

CVE-2018-25426 Overview

CVE-2018-25426 is a denial of service vulnerability in WinMTR version 0.91, a Windows-based network diagnostic tool combining traceroute and ping functionality. The flaw allows attackers to crash the application by supplying a malformed payload file containing a large buffer of repeated characters. A specially crafted input file of 238 bytes triggers a buffer overflow condition that terminates the process. The weakness is classified under CWE-120: Buffer Copy without Checking Size of Input. No vendor patch is referenced in available advisories, and the affected product is a community network utility rather than enterprise infrastructure.

Critical Impact
Attackers can crash WinMTR 0.91 reliably by delivering a 238-byte malformed payload file, disrupting network diagnostic operations.

Affected Products

WinMTR 0.91 (Windows)
Distributions sourced from the WinMTR Download Page
Any deployment relying on WinMTR for traceroute or latency diagnostics

Discovery Timeline

2026-05-30 - CVE-2018-25426 published to the National Vulnerability Database
2026-06-03 - Last updated in NVD database

Technical Details for CVE-2018-25426

Vulnerability Analysis

The vulnerability resides in how WinMTR 0.91 parses payload input files. The application reads attacker-controlled file contents into a fixed-size buffer without validating the input length against the destination capacity. When the input exceeds the buffer boundary, adjacent memory is overwritten and the process terminates abnormally. Public proof-of-concept material at Exploit-DB #45769 demonstrates that 238 bytes of repeated characters are sufficient to trigger the crash. The VulnCheck Advisory for WinMTR confirms the denial of service classification.

Root Cause

The root cause is missing bounds checking during file parsing, consistent with [CWE-120]. WinMTR copies data from a user-supplied payload file into a stack or static buffer using an unbounded copy operation. The application trusts the file contents to remain within an expected size envelope and performs no length validation before the copy. This pattern is a classic buffer overflow primitive in C/C++ code that uses functions such as strcpy or unchecked memcpy against fixed-size destinations.

Attack Vector

Exploitation requires the victim to load an attacker-supplied payload file into WinMTR. Delivery methods include email attachments, shared network folders, or files downloaded from untrusted sources. Once processed, the malformed input overwrites buffer boundaries and crashes the application. The current public exploit produces denial of service only; reliable code execution has not been demonstrated in the available references. The vulnerability is described as network-reachable when payload files originate from remote sources, but exploitation depends on user interaction to open the crafted file.

No verified exploitation code is reproduced here. Technical details are available through Exploit-DB #45769.

Detection Methods for CVE-2018-25426

Indicators of Compromise

Unexpected termination or crash dumps generated by WinMTR.exe on Windows endpoints
Presence of payload files near WinMTR.exe containing long runs of repeated characters at or above 238 bytes
Windows Error Reporting (WER) entries referencing WinMTR.exe with access violation exception codes such as 0xC0000005

Detection Strategies

Inventory endpoints running WinMTR 0.91 by hashing or version-checking the WinMTR.exe binary across managed systems
Alert on application crash events (Event ID 1000) where the faulting module is WinMTR.exe
Inspect file shares and mail gateways for payload files associated with WinMTR that contain abnormal repeating byte patterns

Monitoring Recommendations

Forward Windows Application and WER logs to a centralized analytics platform for correlation of repeated WinMTR.exe crashes
Track process execution telemetry to identify hosts where WinMTR is launched against externally sourced input files
Review egress and download logs for retrieval of WinMTR binaries or payload files from untrusted origins

How to Mitigate CVE-2018-25426

Immediate Actions Required

Identify and inventory all installations of WinMTR 0.91 across the environment
Restrict execution of WinMTR to administrative users who require network diagnostics
Block delivery of unsolicited WinMTR payload files through email and web gateways
Replace WinMTR 0.91 with an actively maintained alternative such as the upstream mtr project or native Windows tools (tracert, pathping)

Patch Information

No vendor patch is referenced in the available advisories for WinMTR 0.91. The WinMTR Official Tool site hosts the affected version, and no fixed release has been published in the references associated with CVE-2018-25426. Organizations should treat the application as end-of-life and migrate to supported tooling.

Workarounds

Remove WinMTR 0.91 from systems where it is not operationally required
Apply application allow-listing to prevent execution of WinMTR.exe outside approved use cases
Configure file integrity monitoring to alert on creation of WinMTR payload files in user profile directories
Use Windows AppLocker or Windows Defender Application Control to restrict launch of the vulnerable binary

bash

# Example AppLocker rule (PowerShell) to deny execution of WinMTR.exe
New-AppLockerPolicy -RuleType Publisher,Hash,Path `
  -User Everyone `
  -Optimize `
  -FileInformation (Get-AppLockerFileInformation -Path 'C:\Program Files\WinMTR\WinMTR.exe') `
  | Set-AppLockerPolicy -Merge