Vulnerability identifier: #VU71771

Vulnerability risk: High

CVSSv3.1: 7.3 [CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H/E:P/RL:O/RC:C]

CVE-ID: CVE-2023-25136

CWE-ID: CWE-415

Exploitation vector: Network

Exploit availability: Yes

Vulnerable software:
OpenSSH
Server applications / Remote management servers, RDP, SSH

Vendor: OpenSSH

Description

The vulnerability allows a remote attacker to potentially execute arbitrary code on the target system.

The vulnerability exists due to a boundary error within the sshd(8) daemon. A remote non-authenticated attacker can send  specially crafted data to the application, trigger a double free error and execute arbitrary code on the target system.

The vendor believes exploitation of this vulnerability has limitations as double free occurs "in the unprivileged pre-auth process that is subject to chroot(2) and is further sandboxed on most major platforms". Nevertheless we assign a high risk to this vulnerability.

Mitigation
Install updates from vendor's website.

Vulnerable software versions

OpenSSH: 9.1p1

---

External links
http://www.openssh.com/releasenotes.html#9.2
http://github.com/openssh/openssh-portable/commit/486c4dc3b83b4b67d663fb0fa62bc24138ec3946
http://bugzilla.mindrot.org/show_bug.cgi?id=3522

---

Q & A

Can this vulnerability be exploited remotely?

Yes. This vulnerability can be exploited by a remote non-authenticated attacker via the Internet.

Is there known malware, which exploits this vulnerability?

No. We are not aware of malware exploiting this vulnerability. However, proof of concept for this vulnerability is available.