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CVE CVE-2024-6387 High Vulnerability ResearchNetwork Security

CVE-2024-6387 — OpenSSH sshd signal-handler race condition

A reference CVE report template covering OpenSSH's regreSSHion vulnerability, its affected release range, impact, and remediation path.

by KSAL Research Team Reference template

Research summary

Abstract

CVE-2024-6387 is a security regression in the OpenSSH server (sshd) that introduces a race condition in signal handling. The public record describes an unauthenticated remote attack condition, with exploitation dependent on timing and platform characteristics. This page is a third-party reference template for the KSAL research archive, not a vulnerability discovered or independently validated by KSAL.

Scope and provenance

This entry demonstrates the report format KSAL will use for CVEs and related open-source security reports. It summarizes public third-party records and is not an original KSAL finding, disclosure, or exploit-validation result.

The primary references for this template are the NVD record and the OpenSSH 9.8 release notes. Product status and affected-version applicability should always be checked against the relevant operating-system vendor advisory before taking action.

Vulnerability summary

The issue is a regression of an earlier OpenSSH signal-handler race condition. The public CVE description states that an unauthenticated remote attacker may be able to trigger the condition by failing to authenticate within the server’s configured time period. The security impact depends on timing, architecture, libc, address-space-layout-randomization behavior, and downstream packaging.

The OpenSSH project describes the vulnerable portable release range as 8.5p1 through 9.7p1, inclusive, and identifies OpenSSH 9.8 as containing the fix. It also notes that successful exploitation was demonstrated under lab conditions on 32-bit Linux/glibc systems with ASLR; those conditions are important context and should not be silently generalized to every deployment.

Impact

The associated CVSS 3.1 vector is AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H, with a base score of 8.1 (High). The vector communicates a network-reachable, high-complexity, unauthenticated condition with potentially high impact to confidentiality, integrity, and availability.

The score is a rating of the published vulnerability record. It is not evidence that a particular host is exploitable, compromised, or affected without first confirming its OpenSSH build, vendor backports, platform, and configuration.

Validation boundary

No exploit attempt or live-target validation is performed by this reference entry. A real KSAL report will record the exact authorized project and release, the safe reproduction method, the concrete observed effect, the test boundary, and whether the result is a true positive, a duplicate, or unresolved.

That distinction is part of the template: a source-level candidate, advisory, or scanner alert is not presented as a confirmed finding without reproducible application-level evidence and release applicability.

Remediation

Operators should upgrade to OpenSSH 9.8p1 or to the fixed package supplied by their operating-system vendor. Where an immediate upgrade is not possible, follow the vendor advisory for interim mitigations and monitor authentication and service logs for unusual connection behavior. Confirm the resulting package version and vendor patch status after remediation.

Disclosure timeline

DateEvent
2024-07-01CVE record published and OpenSSH 9.8 released with the security fix.
2026-09-04KSAL publishes this public reference template in the Research archive.

References

  1. NVD — CVE-2024-6387
  2. OpenSSH 9.8 release notes
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