CVE-2023-6004: 
NixOS vulnerability analysis and mitigation

CVE-2023-6004 is a security vulnerability discovered in libssh, affecting versions 0.8.0 prior to 0.9.8 and 0.10.0 prior to 0.10.6. The vulnerability was disclosed on January 3, 2024, and involves unchecked hostname syntax in the ProxyCommand or ProxyJump features on the client side (LibSSH Advisory).

The vulnerability exists in libssh's implementation of ProxyCommand and ProxyJump features, where unchecked hostname syntax on the client side can be exploited. The issue has a CVSS v3.1 base score of 4.8 (Medium) with the vector string CVSS:3.1/AV:L/AC:L/PR:L/UI:R/S:U/C:L/I:L/A:L, indicating local access is required and user interaction is necessary for exploitation (NVD, Red Hat).

When successfully exploited, this vulnerability could lead to disclosure of sensitive information, addition or modification of data, or Denial of Service (DoS). The attack requires user interaction and local access to be effective (NetApp Advisory).

The primary mitigation is to upgrade to libssh versions 0.9.8 or 0.10.6 or later, which contain the security fixes. For systems that cannot be immediately updated, the recommended workaround is to sanitize hostname input (LibSSH Advisory). Multiple vendors have released security updates to address this vulnerability, including Red Hat through RHSA-2024:2504 and RHSA-2024:3233 (Red Hat Errata).