External risk intelligence

Crashmail Stack Buffer Overflow Remote Code Execution

CVE advisorySeverity: CRITICAL (CVSS 9.3)

CVE-2018-25223

CrashMail is a FidoNet-style mailer/tosser utility typically used in private, legacy, or hobbyist offline message networks. It is not an internet-facing web server, edge gateway, or public-facing service, and its deployment is generally isolated from the public internet.

Out-of-bounds Write

Ftnapps Crashmail Ii

1.6 and earlier

Halo Surface Signal: 1 out of 5 — much less likely to be public-facing.

External exposure likelihood

Horizon Alert

Summary of the vulnerability and why it matters

A critical vulnerability has been identified in Crashmail, a messaging application, that could allow remote attackers to execute arbitrary code or cause a denial of service. While the technology is not typically internet-facing, confirming its presence and exposure is important.

Code execution or denial of service risk.
Impacts older, specialized messaging systems.
Confirm relevance and exposure.

Attack Path

How an attacker could exploit the issue

Attackers can remotely send specially crafted input to the application, targeting a buffer overflow vulnerability. This can lead to the execution of arbitrary code or a denial of service if the attempt fails.

Requires no authentication or special privileges.
Triggered by sending malicious data to the application.
Enables arbitrary code execution or denial of service.

Live Threat

Current exploitation, exposure, and threat context

A stack-based buffer overflow vulnerability in Crashmail could allow remote attackers to execute arbitrary code, potentially impacting the application's service behavior. Failed exploitation attempts may lead to denial of service.

Application code execution.
Malicious input sent over the network.
Service disruption or unauthorized code execution.

Operational Fix

Recommended remediation, mitigation, and detection steps

This vulnerability in Crashmail 1.6 primarily impacts the application owner and infrastructure teams responsible for maintaining the Crashmail service. The first practical step is to determine the scope of Crashmail deployment within the organization, assess its exposure to external networks, and confirm the business criticality of any instances, then engage the accountable owner to prioritize and plan remediation.

Application owner must verify instances.
Confirm external reachability and business impact.
Plan remediation based on risk and vendor input.

Supplementary metadata

CVSS vector

Validate whether this threat affects your internet-facing exposure.

Halo Threat Intelligence helps prioritize remediation with Halo Surface Signal and H/A/L/O context. Start exposure validation with a free external attack surface trial.

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Frequently asked questions

What is Crashmail and how is it used?

Crashmail II is a specialized software utility designed to handle message tossing and routing for FidoNet, a legacy network protocol used to exchange messages between hobbyist bulletin board systems. It functions as a backend tool for processing mail packets rather than a modern web application, typically operating within private or offline message relay environments to manage specialized data flows.

What is the stack-based buffer overflow in CVE-2018-25223?

This vulnerability, classified as CWE-787, occurs when the software writes more data to a specific memory area, called the stack, than it can hold. Because the application fails to properly check the size of incoming data, an attacker can overwrite adjacent memory. In this context, it allows them to inject and run their own instructions or force the program to crash, leading to a loss of service.

How does an attacker trigger this vulnerability?

An attacker initiates the vulnerability by sending a specially formatted data packet directly to the application over the network. The bug is triggered when the software attempts to process this malicious input. It is important to note that standard, well-formed messages or routine traffic that adheres to expected length limits will not trigger this overflow.

Is my system at risk according to Halo Surface Signal?

According to Halo Surface Signal, risk is very unlikely. Crashmail is typically used in private or hobbyist networks that are not exposed to the public internet. Because the software is generally isolated from external traffic, it does not share the same risk profile as an internet-facing gateway or public server, making direct remote exploitation difficult in most deployments.

What should I do if I am running Crashmail?

Begin by identifying all servers in your environment where Crashmail is installed. Determine if any of these instances are reachable from external networks or if they are truly isolated within your private infrastructure. Once you have mapped your deployments, coordinate with the owners of these systems to assess their business role and plan for updates or security configurations provided by the vendor.

References

Written by Nicholas Merritt

Nicholas Merritt is VP of Security Solutions at Halo Security. With more than 25 years across application security, vulnerability prioritization, and offensive security, he helps teams translate threat data into practical exposure validation and remediation focus. He authors Halo Threat Intelligence CVE advisories using Halo Surface Signal and H/A/L/O context to prioritize internet-facing risk.