Why does CVE-2024-6387 create outsized risk even though exploitation is difficult?

Why the risk is outsized compared with the difficulty of exploitation

CVE-2024-6387 is a good example of why exploitability and impact are separate questions. A vulnerability can be technically hard to weaponise and still be high priority if the payoff is remote code execution as root on a widely exposed service. That combination turns one successful exploit into a complete trust boundary collapse, not a limited foothold.

The practical risk is not the probability of one attempt succeeding, but the consequence if it does. NIST National Vulnerability Database and the CVE Program are useful starting points because they anchor the issue in a published, trackable record rather than informal reporting. For prioritisation, the key question is whether the vulnerable SSH service is reachable and whether root-level compromise would expose adjacent systems or privileged operational paths.

Difficulty also tends to be situational. Exploitation may be harder in some builds, on some architectures, or under some timing conditions, but defenders still have to assume that a working exploit will be reused at scale once it exists. That is why a single exposed instance matters: the attacker does not need repeatable success everywhere, only enough success somewhere to gain privileged execution and then pivot.

What makes a hard exploit still dangerous in practice

The severity comes from the shape of the outcome, not the elegance of the exploit. If compromise yields root, the attacker can disable protections, alter logs, deploy persistence, and use the host as a staging point for lateral movement. A vulnerable SSH daemon is especially sensitive because SSH is often present on internet-facing systems, administrative jump hosts, and infrastructure nodes that already sit close to high-value assets.

This is also why exploit difficulty should not be confused with exploit value. CISA Known Exploited Vulnerabilities Catalog is the clearest operational reminder that confirmed exploitation status matters more than abstract ease of exploitation. Once an issue is weaponised, defenders usually face a short response window, especially when the affected service is public and the control failure is concentrated in one high-privilege daemon.

In SSH-related incidents, the blast radius is amplified by what the service can reach rather than by the service alone. A root shell on the gateway, bastion, or management node often provides credentials, session material, configuration files, and trust relationships that were never meant to be exposed to an unauthorised party.

Why prioritisation should follow impact, exposure, and privilege

The correct prioritisation model is to combine exploitability with exposure and privilege, then ask what the first successful compromise would enable. FIRST EPSS is useful for estimating likelihood, but likelihood alone is not enough when the consequence is root-level execution on an externally reachable service. For an internet-facing SSH service, the risk score should rise sharply if the host is shared, privileged, or able to reach management networks.

That is also why defenders should treat this class of issue as more than a patching task. The security decision is whether the vulnerable service can be isolated, constrained, or removed from exposure before a working exploit is broadly available. When the answer is no, the environment is relying on the assumption that attackers will continue to fail, which is not a sound control objective.

For practitioners who want a broader view of exploitation patterns and post-compromise movement, MITRE ATT&CK Enterprise Matrix is a useful companion because it frames what root compromise typically enables next, including privilege escalation, credential access, and lateral movement.

Risk and Threat Considerations

When a remote code execution flaw lands in a public SSH path, the main risk is not repeated failure, it is one successful entry that immediately grants high trust and broad control. The exploit may be difficult to land, but the target environment usually cannot tolerate even one success because root access collapses containment and makes stealthier follow-on activity easier.

Failure mechanism: Attackers exploit a narrow timing or parser weakness, then convert one successful crash or code path into unauthenticated execution as root on an exposed host.

Impact: The compromise can become full-system control, allowing persistence, defence evasion, lateral movement, and access to adjacent privileged assets.

Practitioner Guidance

What to prioritise: Prioritise internet-facing SSH endpoints, then rank any system that has administrative reach, shared trust, or stored credentials above ordinary servers. If the vulnerable host can touch management networks or deploy keys, treat it as a containment problem, not just a software update ticket.

What to verify: Verify the exact exposure path, the patched version actually running in production, and whether compensating controls such as segmentation, allowlisting, or service isolation reduce the reachable attack surface. A patch that has not been deployed everywhere the service listens should not be treated as closure.

Practitioner takeaway: Low exploitability only lowers the odds of compromise, it does not meaningfully reduce the urgency when the successful outcome is root on a publicly reachable system.

Related resources from NHI Mgmt Group

• Why does an OpenSSH race condition create meaningful risk even when exploitation appears difficult?
• Why does CVE-2024-6387 create serious risk for Linux systems using glibc and OpenSSH?
• Why do non-human identities create more risk than many human accounts?
• Why do non-human identities create more remediation risk than many human accounts?