CVE-2023-28436 | Non-interactive Tailscale SSH sessions on FreeBSD may use the effective group ID of the tailscaled process

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.

Published: 2023-03-23 Last update: 2024-11-21 Assigner: [email protected] Source: [email protected]
NVD Status：Modified，CVE State: published
View at NVD, CVE.org, EUVD

CVE-2023-28436 is rated Low Risk (38.3/100): CVSS Medium severity, with low exploitation likelihood (EPSS 0.21%). Monitor for updates and reassess as exploit intelligence or EPSS changes.

Risk is dynamic; we continuously reassess and refresh what is shown on this page as upstream context changes.

Exploit prediction scoring system (EPSS) score for CVE-2023-28436

EPSS lead: Daily EPSS estimates relative likelihood of exploitation; percentile ranks this CVE among scored vulnerabilities (higher = more severe relative rank).

# Date Old EPSS score New EPSS score Delta (New - Old)
1 2026-03-25 0.07% 0.21% +0.15%
2 2025-11-21 0.17% 0.07% -0.11%
3 2025-11-18 — 0.17% —

Full EPSS history (8 records total)

Common vulnerability scoring system (CVSS) metrics for CVE-2023-28436

CVSS metrics for this CVE.

Base score Version Severity Vector Exploitability Impact Score source
5.7 3.1 MEDIUM
CVSS:3.1/AV:A/AC:L/PR:H/UI:R/S:C/C:H/I:N/A:N Click to expand
Attack vector (AV:A)
Attacker has to be nearby on the network—same office, same link, that vibe—not the whole wide internet.
Attack complexity (AC:L)
Once they can reach the bug, pulling it off is straightforward—no weird race conditions or rare setup.
Privileges required (PR:H)
They need powerful rights—admin, root, or similar—before this pays off.
User interaction (UI:R)
A real person has to do something—click, install, enable—otherwise it doesn’t land.
Scope (S:C)
Breaking this can reach past the original component and bite other resources—bigger blast radius.
Confidentiality (C:H)
Serious risk that confidential data gets exposed in a big way.
Integrity (I:N)
Data isn’t meaningfully altered or forged.
Availability (A:N)
Service keeps running; no real outage angle.
 1.2 4.0 [email protected]
8.0 3.1 HIGH
CVSS:3.1/AV:A/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H Click to expand
Attack vector (AV:A)
Attacker has to be nearby on the network—same office, same link, that vibe—not the whole wide internet.
Attack complexity (AC:L)
Once they can reach the bug, pulling it off is straightforward—no weird race conditions or rare setup.
Privileges required (PR:L)
A normal user session is enough; they don’t have to be admin.
User interaction (UI:N)
Nobody has to click “OK” or open a trap file; it can work without a victim helping.
Scope (S:U)
Damage stays in the same “trust bubble” as the broken component—no big spill into unrelated systems.
Confidentiality (C:H)
Serious risk that confidential data gets exposed in a big way.
Integrity (I:H)
They could widely tamper with or forge data—trust in the data is badly hurt.
Availability (A:H)
Could take the service down hard or make it unusable for people who depend on it.
 2.1 5.9 [email protected]

Weakness enumeration for CVE-2023-28436

GitHub Security Advisory for CVE-2023-28436

GHSA-vfgq-g5x8-g595 · Severity: medium · Ecosystem: go — Non-interactive Tailscale SSH sessions on FreeBSD may use the effective group ID of the tailscaled process

Affected software / configurations for CVE-2023-28436

Vendor Product Version Raw CPE
tailscale tailscale >= 1.34, < 1.38.2 cpe:2.3:a:tailscale:tailscale:*:*:*:*:*:*:*:*

References for CVE-2023-28436

cvelogic Threat Intelligence