Tailscale is software for using Wireguard and multi-factor authentication (MFA). A vulnerability identified in the implementation of Tailscale SSH starting in version 1.34.0 and prior to prior to 1.38.2 in FreeBSD allows commands to be run with a higher privilege group ID than that specified in Tailscale SSH access rules. A difference in the behavior of the FreeBSD `setgroups` system call from POSIX meant that the Tailscale client running on a FreeBSD-based operating system did not appropriately restrict groups on the host when using Tailscale SSH. When accessing a FreeBSD host over Tailscale SSH, the egid of the tailscaled process was used instead of that of the user specified in Tailscale SSH access rules. Tailscale SSH commands may have been run with a higher privilege group ID than that specified in Tailscale SSH access rules if they met all of the following criteria: the destination node was a FreeBSD device with Tailscale SSH enabled; Tailscale SSH access rules permitted access for non-root users; and a non-interactive SSH session was used. Affected users should upgrade to version 1.38.2 to remediate the issue.

There are packages installed that are affected by a vulnerability referenced in the following CVE:

  - Tailscale is software for using Wireguard and multi-factor authentication (MFA). A vulnerability
    identified in the implementation of Tailscale SSH starting in version 1.34.0 and prior to prior to 1.38.2
    in FreeBSD allows commands to be run with a higher privilege group ID than that specified in Tailscale SSH
    access rules. A difference in the behavior of the FreeBSD `setgroups` system call from POSIX meant that
    the Tailscale client running on a FreeBSD-based operating system did not appropriately restrict groups on
    the host when using Tailscale SSH. When accessing a FreeBSD host over Tailscale SSH, the egid of the
    tailscaled process was used instead of that of the user specified in Tailscale SSH access rules. Tailscale
    SSH commands may have been run with a higher privilege group ID than that specified in Tailscale SSH
    access rules if they met all of the following criteria: the destination node was a FreeBSD device with
    Tailscale SSH enabled; Tailscale SSH access rules permitted access for non-root users; and a non-
    interactive SSH session was used. Affected users should upgrade to version 1.38.2 to remediate the issue.
    (CVE-2023-28436)

The version of FreeBSD installed on the remote host is prior to tested version. It is, therefore, affected by a vulnerability as referenced in the 1b15a554-c981-11ed-bb39-901b0e9408dc advisory.

  - Tailscale team reports: A vulnerability identified in the implementation of Tailscale SSH in FreeBSD     allowed commands to be run with a higher privilege group ID than that specified           by Tailscale SSH     access rules. (CVE-2023-28436)

Note that Nessus has not tested for this issue but has instead relied only on the application's self-reported version number.

ID	Name	Product	Family	Severity
419295	SCA: security update for tailscale.com (GHSA-vfgq-g5x8-g595)	Tenable Cloud Security	SCA Checks	high
419295	SCA: security update for tailscale.com (GHSA-vfgq-g5x8-g595)	Tenable Self-Hosted Container Security	SCA Checks	high
173329	FreeBSD : tailscale -- security vulnerability in Tailscale SSH (1b15a554-c981-11ed-bb39-901b0e9408dc)	Nessus	FreeBSD Local Security Checks	high

Detections

Analytics

CVE-2023-28436

high

Tenable Plugins

high

high

high