CVE-2024-7589: OpenSSH pre-authentication async signal safety issue
First published: Sun Aug 11 2024(Updated: )
A signal handler in sshd(8) may call a logging function that is not async-signal-safe. The signal handler is invoked when a client does not authenticate within the LoginGraceTime seconds (120 by default). This signal handler executes in the context of the sshd(8)'s privileged code, which is not sandboxed and runs with full root privileges. This issue is another instance of the problem in CVE-2024-6387 addressed by FreeBSD-SA-24:04.openssh. The faulty code in this case is from the integration of blacklistd in OpenSSH in FreeBSD. As a result of calling functions that are not async-signal-safe in the privileged sshd(8) context, a race condition exists that a determined attacker may be able to exploit to allow an unauthenticated remote code execution as root.
Credit: secteam@freebsd.org
| Affected Software | Affected Version | How to fix |
|---|---|---|
| FreeBSD Kernel | <13.0 | |
| FreeBSD Kernel | >=13.1<13.3 | |
| FreeBSD Kernel | =13.3-p1 | |
| FreeBSD Kernel | =13.3-p2 | |
| FreeBSD Kernel | =13.3-p3 | |
| FreeBSD Kernel | =13.3-p4 | |
| FreeBSD Kernel | =14.0-beta5 | |
| FreeBSD Kernel | =14.0-p1 | |
| FreeBSD Kernel | =14.0-p2 | |
| FreeBSD Kernel | =14.0-p3 | |
| FreeBSD Kernel | =14.0-p4 | |
| FreeBSD Kernel | =14.0-p5 | |
| FreeBSD Kernel | =14.0-p6 | |
| FreeBSD Kernel | =14.0-p7 | |
| FreeBSD Kernel | =14.0-p8 | |
| FreeBSD Kernel | =14.0-rc3 | |
| FreeBSD Kernel | =14.0-rc4-p1 | |
| FreeBSD Kernel | =14.1-p1 | |
| FreeBSD Kernel | =14.1-p2 |
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Reference Links
Frequently Asked Questions
What is the severity of CVE-2024-7589?
CVE-2024-7589 has a medium severity rating due to potential issues with asynchronous signal safety in the sshd process.
How do I fix CVE-2024-7589?
To fix CVE-2024-7589, update your FreeBSD systems to a version that has patched this vulnerability.
Which versions of FreeBSD are affected by CVE-2024-7589?
CVE-2024-7589 affects FreeBSD versions up to 13.0 and versions in the 13.1 to 14.1 range.
What does the signal handler issue in CVE-2024-7589 involve?
The signal handler in CVE-2024-7589 may call a logging function that is not async-signal-safe, potentially leading to system instability.
How can I determine if my FreeBSD system is vulnerable to CVE-2024-7589?
You can determine if your FreeBSD system is vulnerable to CVE-2024-7589 by checking your version against the affected versions listed for this vulnerability.
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