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

Status: published. Published: 2024-07-08. Updated: 2026-11-03.

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.

## Remediation

- workaround: The process is identical to CVE-2024-6387, by disabling LoginGraceTime. See that CVE page for additional details. (source: CNA: redhat)

## Affected products and versions

-  /  (OpenSSH): Version range not reported. Source: CNA: redhat
- Red Hat / Red Hat Enterprise Linux 9 (openssh): ≥ 0:8.7p1-38.el9_4.4; < * (unaffected, rpm). Source: CNA: redhat
- Red Hat / Red Hat Enterprise Linux 9.0 Update Services for SAP Solutions (openssh): ≥ 0:8.7p1-12.el9_0.3; < * (unaffected, rpm). Source: CNA: redhat
- Red Hat / Red Hat Enterprise Linux 9.2 Extended Update Support (openssh): ≥ 0:8.7p1-30.el9_2.7; < * (unaffected, rpm). Source: CNA: redhat
- Red Hat / Red Hat OpenShift Container Platform 4.13 (openshift/ose-rhel-coreos-9): ≥ 413.92.202408122222-0; < * (unaffected, rpm). Source: CNA: redhat
- Red Hat / Red Hat OpenShift Container Platform 4.14 (openshift/ose-rhel-coreos-9): ≥ 414.92.202407300859-0; < * (unaffected, rpm). Source: CNA: redhat
- Red Hat / Red Hat OpenShift Container Platform 4.15 (openshift/ose-rhel-coreos-9): ≥ 415.92.202407301159-0; < * (unaffected, rpm). Source: CNA: redhat
- Red Hat / Red Hat OpenShift Container Platform 4.16 (openshift/ose-rhel-coreos-9): ≥ 416.94.202407171205-0; < * (unaffected, rpm). Source: CNA: redhat
- Red Hat / Red Hat Enterprise Linux 10 (openssh): Version range not reported. Source: CNA: redhat
- Red Hat / Red Hat Enterprise Linux 6 (openssh): Version range not reported. Source: CNA: redhat
- Red Hat / Red Hat Enterprise Linux 7 (openssh): Version range not reported. Source: CNA: redhat
- Red Hat / Red Hat Enterprise Linux 8 (openssh): Version range not reported. Source: CNA: redhat
- Siemens / SIMATIC S7-1500 CPU 1518-4 PN/DP MFP: ≥ V3.1.0; < V3.1.5 (affected, custom). Source: ADP: siemens-SADP
- Siemens / SIMATIC S7-1500 CPU 1518F-4 PN/DP MFP: ≥ V3.1.0; < V3.1.5 (affected, custom). Source: ADP: siemens-SADP
- Siemens / SIPLUS S7-1500 CPU 1518-4 PN/DP MFP: ≥ V3.1.0; < V3.1.5 (affected, custom). Source: ADP: siemens-SADP

## Severity and prioritization

- CVSS 3.1: 7 (high); CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:L/A:H; source: CNA: redhat

- CVSS 3.1: 7 (high); CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:L/A:H; source: NVD: secalert@redhat.com

- CISA KEV: No listing in collected sources

- EPSS: 27.93% as of 2026-11-03; percentile 98.10%

- SSVC: exploitation none; automatable no; technical impact total; source ADP: CISA-ADP

- Weaknesses: CWE-364

## Exploit evidence

No exploit evidence in collected sources. This is not proof of no exploitation.

## References

- https://access.redhat.com/errata/RHSA-2024:4457 (CNA: redhat; vendor-advisory, x_refsource_REDHAT)

- https://access.redhat.com/errata/RHSA-2024:4613 (CNA: redhat; vendor-advisory, x_refsource_REDHAT)

- https://access.redhat.com/errata/RHSA-2024:4716 (CNA: redhat; vendor-advisory, x_refsource_REDHAT)

- https://access.redhat.com/errata/RHSA-2024:4910 (CNA: redhat; vendor-advisory, x_refsource_REDHAT)

- https://access.redhat.com/errata/RHSA-2024:4955 (CNA: redhat; vendor-advisory, x_refsource_REDHAT)

- https://access.redhat.com/errata/RHSA-2024:4960 (CNA: redhat; vendor-advisory, x_refsource_REDHAT)

- https://access.redhat.com/errata/RHSA-2024:5444 (CNA: redhat; vendor-advisory, x_refsource_REDHAT)

- https://access.redhat.com/security/cve/CVE-2024-6409 (CNA: redhat; vdb-entry, x_refsource_REDHAT)

- https://bugzilla.redhat.com/show_bug.cgi?id=2295085 (CNA: redhat; issue-tracking, x_refsource_REDHAT)

- http://www.openwall.com/lists/oss-security/2024/07/08/2 (ADP: CVE; x_transferred)

- http://www.openwall.com/lists/oss-security/2024/07/09/2 (ADP: CVE; x_transferred)

- http://www.openwall.com/lists/oss-security/2024/07/09/5 (ADP: CVE; x_transferred)

- http://www.openwall.com/lists/oss-security/2024/07/10/1 (ADP: CVE; x_transferred)

- http://www.openwall.com/lists/oss-security/2024/07/10/2 (ADP: CVE; x_transferred)

- https://access.redhat.com/errata/RHSA-2024:4457 (ADP: CVE; vendor-advisory, x_refsource_REDHAT, x_transferred)

- https://access.redhat.com/errata/RHSA-2024:4613 (ADP: CVE; vendor-advisory, x_refsource_REDHAT, x_transferred)

- https://access.redhat.com/errata/RHSA-2024:4716 (ADP: CVE; vendor-advisory, x_refsource_REDHAT, x_transferred)

- https://access.redhat.com/security/cve/CVE-2024-6409 (ADP: CVE; vdb-entry, x_refsource_REDHAT, x_transferred)

- https://almalinux.org/blog/2024-07-09-cve-2024-6409/ (ADP: CVE; x_transferred)

- https://bugzilla.redhat.com/show_bug.cgi?id=2295085 (ADP: CVE; issue-tracking, x_refsource_REDHAT, x_transferred)

- https://bugzilla.suse.com/show_bug.cgi?id=1227217 (ADP: CVE; x_transferred)

- https://explore.alas.aws.amazon.com/CVE-2024-6409.html (ADP: CVE; x_transferred)

- https://github.com/openela-main/openssh/commit/c00da7741d42029e49047dd89e266d91dcfbffa0 (ADP: CVE; x_transferred)

- https://security-tracker.debian.org/tracker/CVE-2024-6409 (ADP: CVE; x_transferred)

- https://security.netapp.com/advisory/ntap-20240712-0003/ (ADP: CVE; x_transferred)

- https://sig-security.rocky.page/issues/CVE-2024-6409/ (ADP: CVE; x_transferred)

- https://ubuntu.com/security/CVE-2024-6409 (ADP: CVE; x_transferred)

- https://www.suse.com/security/cve/CVE-2024-6409.html (ADP: CVE; x_transferred)

- https://cert-portal.siemens.com/productcert/html/ssa-398330.html (ADP: siemens-SADP)

- https://access.redhat.com/errata/RHSA-2024:4457 (secalert@redhat.com)

- https://access.redhat.com/errata/RHSA-2024:4613 (secalert@redhat.com)

- https://access.redhat.com/errata/RHSA-2024:4716 (secalert@redhat.com)

- https://access.redhat.com/errata/RHSA-2024:4910 (secalert@redhat.com)

- https://access.redhat.com/errata/RHSA-2024:4955 (secalert@redhat.com)

- https://access.redhat.com/errata/RHSA-2024:4960 (secalert@redhat.com)

- https://access.redhat.com/errata/RHSA-2024:5444 (secalert@redhat.com)

- https://access.redhat.com/security/cve/CVE-2024-6409 (secalert@redhat.com)

- https://bugzilla.redhat.com/show_bug.cgi?id=2295085 (secalert@redhat.com)

- http://www.openwall.com/lists/oss-security/2024/07/08/2 (af854a3a-2127-422b-91ae-364da2661108)

- http://www.openwall.com/lists/oss-security/2024/07/09/2 (af854a3a-2127-422b-91ae-364da2661108)

- http://www.openwall.com/lists/oss-security/2024/07/09/5 (af854a3a-2127-422b-91ae-364da2661108)

- http://www.openwall.com/lists/oss-security/2024/07/10/1 (af854a3a-2127-422b-91ae-364da2661108)

- http://www.openwall.com/lists/oss-security/2024/07/10/2 (af854a3a-2127-422b-91ae-364da2661108)

- https://access.redhat.com/errata/RHSA-2024:4457 (af854a3a-2127-422b-91ae-364da2661108)

- https://access.redhat.com/errata/RHSA-2024:4613 (af854a3a-2127-422b-91ae-364da2661108)

- https://access.redhat.com/errata/RHSA-2024:4716 (af854a3a-2127-422b-91ae-364da2661108)

- https://access.redhat.com/security/cve/CVE-2024-6409 (af854a3a-2127-422b-91ae-364da2661108)

- https://almalinux.org/blog/2024-07-09-cve-2024-6409/ (af854a3a-2127-422b-91ae-364da2661108)

- https://bugzilla.redhat.com/show_bug.cgi?id=2295085 (af854a3a-2127-422b-91ae-364da2661108)

- https://bugzilla.suse.com/show_bug.cgi?id=1227217 (af854a3a-2127-422b-91ae-364da2661108)

- https://explore.alas.aws.amazon.com/CVE-2024-6409.html (af854a3a-2127-422b-91ae-364da2661108)

- https://github.com/openela-main/openssh/commit/c00da7741d42029e49047dd89e266d91dcfbffa0 (af854a3a-2127-422b-91ae-364da2661108)

- https://security-tracker.debian.org/tracker/CVE-2024-6409 (af854a3a-2127-422b-91ae-364da2661108)

- https://security.netapp.com/advisory/ntap-20240712-0003/ (af854a3a-2127-422b-91ae-364da2661108)

- https://sig-security.rocky.page/issues/CVE-2024-6409/ (af854a3a-2127-422b-91ae-364da2661108)

- https://ubuntu.com/security/CVE-2024-6409 (af854a3a-2127-422b-91ae-364da2661108)

- https://www.suse.com/security/cve/CVE-2024-6409.html (af854a3a-2127-422b-91ae-364da2661108)

- https://cert-portal.siemens.com/productcert/html/ssa-398330.html (0b142b55-0307-4c5a-b3c9-f314f3fb7c5e)

## Provenance

- CNA: redhat: https://www.cve.org/CVERecord?id=CVE-2024-6409; retrieved 2026-11-03; source updated 2026-11-03

- NVD: https://nvd.nist.gov/vuln/detail/CVE-2024-6409; retrieved 2026-11-04; source updated 2026-11-03

- FIRST EPSS: https://api.first.org/data/v1/epss?cve=CVE-2024-6409; retrieved 2026-11-03; source updated Not reported

Revision: 2c038ff7f430339fdbb7c0ab3f385de16c557250733f493c384faf08ec1a377f

Canonical: https://y2.dev/cve/CVE-2024-6409

## Agent and API access

Public CVE pages, Markdown, and JSON are free to read without an account or API key.

- Public catalog: https://y2.dev/cve/index.json. Follow nextCursor with the same search, filters, sort, and limit (1–100). A null cursor marks the end.

- WebMCP: search_cve_disclosures, get_cve_disclosure, get_cve_page_markdown, get_y2_cve_access. Available in compatible browsers.

- Cyber API: https://api.y2.dev/api/v2/cyber/cves and https://api.y2.dev/api/v2/cyber/cves/{cveId}.

- Y2 Pro or Elite: create a workspace API key with the intel:cyber scope and send Authorization: Bearer <Y2_API_KEY>. Setup: https://y2.dev/docs/api/create-key.

- x402: Pay per request without an account or API key. Omit Authorization, read the HTTP 402 PAYMENT-REQUIRED challenge, validate its current requirements, and retry with PAYMENT-SIGNATURE through an authorized payment client. These browser tools never make payments. Guide: https://y2.dev/docs/api/x402.

- OpenAPI: https://y2.dev/api/openapi.yaml. Agent access metadata: https://y2.dev/cve/agent.json.

Collected public records only. Check source status for coverage and freshness.