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Description

9Router before 0.4.44 contains an OS command injection vulnerability in the unauthenticated POST /api/tunnel/tailscale-install endpoint (this route is not covered by the dashboard middleware matcher, so no authorization check is applied). The sudoPassword field from the request body is written to the stdin of a 'sudo -S sh' child process. When sudo does not prompt for a password (the process runs as root, NOPASSWD is configured, or a recent sudo timestamp cache exists), the sudoPassword value is interpreted by sh as a shell command, allowing a remote unauthenticated attacker to execute arbitrary OS commands. Exploitation evidence was first observed by the Shadowserver Foundation on 2026-07-04 (UTC).

PUBLISHED Reserved 2026-07-07 | Published 2026-07-07 | Updated 2026-07-07 | Assigner VulnCheck




CRITICAL: 9.2CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N

CRITICAL: 9.8CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

Problem types

Improper Neutralization of Special Elements used in an OS Command ('OS Command Injection')

Product status

Default status
unaffected

Any version before 0.4.44
affected

0.4.44 (semver)
unaffected

Credits

Vũ Chí Thành (@vcth4nh) reporter

Huỳnh Đức Tin (@Ductinn) reporter

References

github.com/...router/security/advisories/GHSA-g6g7-pvmx-m74p exploit

github.com/...router/security/advisories/GHSA-g6g7-pvmx-m74p (GitHub Security Advisory (GHSA-g6g7-pvmx-m74p)) vendor-advisory

www.vulncheck.com/...parameter-in-tailscale-install-endpoint third-party-advisory

cve.org (CVE-2026-59800)

nvd.nist.gov (CVE-2026-59800)

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