CVE-2024-6409: Openssh: possible remote code execution due to a race condition in signal handling affecting red hat enterprise linux 9

Is it exploited?

Reported, not confirmed by CISA. VulnCheck KEV lists it as exploited in the wild. CISA has not added it to its Known Exploited Vulnerabilities catalog as of 29 Oct 2026.

VulnCheck KEV lists it since 12 Mar 2025. It cites 1 public report, the first from 12 Mar 2025.

• content.kaspersky-labs.com

How likely is exploitation in the next 30 days?

27.9%

EPSS score, percentile 98.1 of all scored records. A probability estimated by FIRST, not a report of exploitation.

How severe?

7.0 High

CVSS v3.1 base score, given by the CNA

What should I do?

CISA has set no required action, because the vulnerability is not in KEV.

Advisories and patches (7)

Which versions are affected?

Unaffected 0:8.7p1-38.el9_4.4; 0:8.7p1-38.el9_4.4; 0:8.7p1-12.el9_0.3; 0:8.7p1-30.el9_2.7; 413.92.202408122222-0; 414.92.202407300859-0; and 2 more

Versions by product

Source: CISA KEV 2026.10.29, as of 29 Oct 2026; VulnCheck KEV, as of 30 Oct 2026; FIRST EPSS, as of 29 Oct 2026; CVE List, as of 30 Oct 2026. About the data.

Description

Openssh: possible remote code execution due to a race condition in signal handling affecting red hat enterprise linux 9

A race condition vulnerability was discovered in how signals are handled by OpenSSH's server (sshd). If a remote attacker does not authenticate within a set time period, then sshd's SIGALRM handler is called asynchronously. However, this signal handler calls various functions that are not async-signal-safe, for example, syslog(). As a consequence of a successful attack, in the worst case scenario, an attacker may be able to perform a remote code execution (RCE) as an unprivileged user running the sshd server.

Source: CVE List, as of 30 Oct 2026. About the data.

What to do

Advisories and patches

• RHSA-2024:4457 (Vendor advisory)
• RHSA-2024:4613 (Vendor advisory)
• RHSA-2024:4716 (Vendor advisory)
• RHSA-2024:4910 (Vendor advisory)
• RHSA-2024:4955 (Vendor advisory)
• RHSA-2024:4960 (Vendor advisory)
• RHSA-2024:5444 (Vendor advisory)

Workaround (from the CVE record)

The process is identical to CVE-2024-6387, by disabling LoginGraceTime. See that CVE page for additional details.

This summary is based on the CVE record as of 30 Oct 2026. Check the vendor's advisory before you act: affected versions and fixes can change.

Affected products and versions

Source: CVE List, as of 30 Oct 2026. About the data.

Timeline

Known exploited Red Hat vulnerabilities

• CVE-2015-3246: Red Hat Libuser Race Condition Vulnerability (added 26 Aug 2026)
• CVE-2015-5287: Red Hat Automatic Bug Reporting Tool Privilege Escalation Vulnerability (added 26 Aug 2026)
• CVE-2018-14667: Red Hat JBoss RichFaces Framework Expression Language Injection Vulnerability (added 28 Sep 2023)
• CVE-2021-3560: Red Hat Polkit Incorrect Authorization Vulnerability (added 12 May 2023)
• CVE-2021-4034: Red Hat Polkit Out-of-Bounds Read and Write Vulnerability (added 27 Jun 2022)