Vulnerability Details : CVE-2023-28436
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.
Products affected by CVE-2023-28436
- cpe:2.3:a:tailscale:tailscale:*:*:*:*:*:*:*:*
Exploit prediction scoring system (EPSS) score for CVE-2023-28436
0.04%
Probability of exploitation activity in the next 30 days
EPSS Score History
~ 6 %
Percentile, the proportion of vulnerabilities that are scored at or less
CVSS scores for CVE-2023-28436
Base Score | Base Severity | CVSS Vector | Exploitability Score | Impact Score | Score Source | First Seen |
---|---|---|---|---|---|---|
8.0
|
HIGH | CVSS:3.1/AV:A/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H |
2.1
|
5.9
|
NIST | |
5.7
|
MEDIUM | CVSS:3.1/AV:A/AC:L/PR:H/UI:R/S:C/C:H/I:N/A:N |
1.2
|
4.0
|
GitHub, Inc. |
CWE ids for CVE-2023-28436
-
The product does not properly assign, modify, track, or check privileges for an actor, creating an unintended sphere of control for that actor.Assigned by: security-advisories@github.com (Primary)
References for CVE-2023-28436
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https://github.com/tailscale/tailscale/releases/tag/v1.38.2
Release 1.38.2 · tailscale/tailscale · GitHubPatch;Release Notes
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https://github.com/tailscale/tailscale/commit/d00c046b723dff6e3775d7d35f891403ac21a47d
ssh/tailssh: fix privilege dropping on FreeBSD; add tests · tailscale/tailscale@d00c046 · GitHubPatch
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https://tailscale.com/security-bulletins/#ts-2023-003
Security Bulletins · TailscaleVendor Advisory
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https://github.com/tailscale/tailscale/security/advisories/GHSA-vfgq-g5x8-g595
Non-interactive Tailscale SSH sessions on FreeBSD may use the effective group ID of the tailscaled process · Advisory · tailscale/tailscale · GitHubMitigation;Vendor Advisory
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