Medium [CVE-2026-73283] Tunnel forwarding restriction bypass
This medium-severity Red Hat Linux advisory covers CVE-2026-73283 affecting Red Hat Enterprise Linux 10, Red Hat Enterprise Linux 6, Red Hat Enterprise Linux 7.
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Summary
A flaw was found in OpenSSH's `sshd` component. The `restrict` keyword, designed to limit tunnel forwarding within the `authorized_keys` file, was not correctly enforced for tunnel forwarding.
This issue could allow a local attacker to bypass intended security restrictions, potentially leading to unauthorized network access or resource usage through tunnels. When processing SSH public key authentication, sshd fails to enforce the restrict keyword in authorized_keys against TUN/TAP tunnel forwarding requests.
An authenticated user holding a restricted key can still establish virtual network interface tunnels if tunnel forwarding is globally enabled on the server. This allows authorized users to bypass intended per-key restriction policies, posing a Moderate impact to confidentiality and integrity.
Red Hat severity: Moderate — CVSS 5.4 (CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:L/I:L/A:N). Weakness: CWE-305.
Affected Red Hat products: Red Hat Enterprise Linux 10; Red Hat Enterprise Linux 6; Red Hat Enterprise Linux 7; Red Hat Enterprise Linux 8; Red Hat Enterprise Linux 9; Red Hat Hardened Images. Red Hat does not currently list a fixing RHSA for this CVE.
Affected products named by the advisory: Red Hat package: openssh.
Affected versions
No affected-version range was extracted from the source record. The vendor advisory is authoritative — check it before change work.
Official advisory · high-confidence parse· fetched 1 hour ago·verify at source
Fixed versions
No fixed release is recorded yet. That does not prove no patch exists — confirm against the vendor advisory.
Official advisory · high-confidence parse· fetched 1 hour ago·verify at source
Mitigation checklist
- Set PermitTunnel no in /etc/ssh/sshd_config to disable TUN/TAP tunnel forwarding server-wide. Alternatively, restrict tunnel permissions for specific users or groups using Match blocks in sshd_config or explicit no-tun directives in authorized_keys.
Official advisory · high-confidence parse· fetched 1 hour ago·verify at source
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