CVE-2024-6409
Published: July 9, 2024Last modified: June 17, 2025
Description
A signal handler race condition vulnerability was found in OpenSSH's server (sshd), where a client does not authenticate within LoginGraceTime seconds (120 by default, 600 in old OpenSSH versions), then sshd's SIGALRM handler is called asynchronously. However, this signal handler calls various functions that are not async-signal-safe, for example, syslog(). This issue leaves it vulnerable to a signal handler race condition on the cleanup_exit() function, which introduces the same vulnerability as CVE-2024-6387 in the unprivileged child of the SSHD server.
Severity score breakdown
| Parameter | Value |
|---|---|
| Base score | 7 |
| Attack Vector | NETWORK |
| Attack complexity | HIGH |
| Privileges required | NONE |
| User interaction | NONE |
| Scope | UNCHANGED |
| Confidentiality | LOW |
| Integrity impact | LOW |
| Availability impact | HIGH |
| Vector | CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:L/A:H |
Status
| Product | Release | Package | Status |
|---|---|---|---|
| Alpaquita Linux | 23 LTS | openssh | Not affected (9.1_p1-r3) |
| Stream | openssh | Not affected (9.3_p1-r7) |
References
- http://www.openwall.com/lists/oss-security/2024/07/08/2
- http://www.openwall.com/lists/oss-security/2024/07/09/2
- http://www.openwall.com/lists/oss-security/2024/07/09/5
- http://www.openwall.com/lists/oss-security/2024/07/10/1
- http://www.openwall.com/lists/oss-security/2024/07/10/2
- 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://almalinux.org/blog/2024-07-09-cve-2024-6409/
- https://bugzilla.redhat.com/show_bug.cgi?id=2295085
- https://bugzilla.suse.com/show_bug.cgi?id=1227217
- https://explore.alas.aws.amazon.com/CVE-2024-6409.html
- https://github.com/openela-main/openssh/commit/c00da7741d42029e49047dd89e266d91dcfbffa0
- https://security-tracker.debian.org/tracker/CVE-2024-6409
- https://security.netapp.com/advisory/ntap-20240712-0003/
- https://sig-security.rocky.page/issues/CVE-2024-6409/
- https://ubuntu.com/security/CVE-2024-6409
- https://www.suse.com/security/cve/CVE-2024-6409.html