# CVE-2026-59999: OpenSSH sshd configuration bypass in DisableForwarding directive

Source: https://junglewise.ai/threats/cve-2026-59999-openssh-sshd-configuration-bypass-in-disableforwarding-directive  
Publisher: Junglewise Threat Intelligence, https://junglewise.ai/threats  
Published: 2026-07-08. Updated: 2026-07-08  
License: CC BY 4.0 with a link back

CVE-2026-59999 · Severity: medium · CVSS 5.9 · Published 2026-07-08

OpenSSH is a widely used tool for secure remote access to servers. A configuration flaw was discovered where the setting intended to disable all forms of traffic forwarding did not correctly override tunnel permissions. This could allow an authorized user to establish network tunnels even when an administrator explicitly intended to block such activity.

Technologies: [OpenBSD Openssh](https://junglewise.ai/threats/technologies/openssh). Vendors: [OpenBSD](https://junglewise.ai/threats/vendors/openbsd).

## Quick answers

**Is CVE-2026-59999 exploited in the wild?** No. Junglewise Threat Intelligence has no report of CVE-2026-59999 being exploited in the wild.

**How severe is CVE-2026-59999?** Medium severity, with a CVSS score of 5.9, published 8 July 2026.

**Which products and versions are affected?** OpenBSD Openssh before 10.4.

**Is there a fix for CVE-2026-59999?** A patch was published on 2026-07-06: OpenSSH 10.4 released with fix. Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.

**How is CVE-2026-59999 attacked?** It is attacked over the network, in a hosted service.

**Am I affected by CVE-2026-59999?** Check whether you run OpenBSD Openssh at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

## Technical details

A logic error in sshd's configuration parsing causes the 'DisableForwarding=yes' directive to fail to override 'PermitTunnel=yes', contrary to documented behavior. This vulnerability allows a remote user with valid authentication to establish Layer 2 or Layer 3 network tunnels if 'PermitTunnel' is enabled, even if the administrator has globally or specifically set 'DisableForwarding' to block such traffic. The attack requires 'PermitTunnel' to be manually enabled, as it is disabled by default. The issue is resolved in OpenSSH version 10.4.

## Affected products

- OpenBSD OpenSSH before 10.4

## Timeline

- 2026-07-06: patched: OpenSSH 10.4 released with fix.
- 2026-07-08: disclosed: CVE-2026-59999 published.

## References

- [https://marc.info/?l=openssh-unix-dev&m=178333966933090&w=2](https://marc.info/?l=openssh-unix-dev&m=178333966933090&w=2)
- [https://www.openssh.org/releasenotes.html](https://www.openssh.org/releasenotes.html)
- [https://www.openwall.com/lists/oss-security/2026/07/06/5](https://www.openwall.com/lists/oss-security/2026/07/06/5)

## Related threats

- [OpenSSH password authentication bypass on musl libc without PAM](https://junglewise.ai/threats/cve-2026-123158-sshd-in-openssh-before-10-6p2-on-linux-when-musl-libc-is-used)
- [In sshd in OpenSSH before 10.5, the restrict keyword (in authorized_keys) was supposed to be applicable to tunnel forwarding but was not.](https://junglewise.ai/threats/cve-2026-73283-in-sshd-in-openssh-before-10-5-the-restrict-keyword-in-authorized)
- [In ssh in OpenSSH before 10.5, a use-after-free for realloc data can occur if a certain pair of remote-forwarding operations are concurrent.](https://junglewise.ai/threats/cve-2026-73282-in-ssh-in-openssh-before-10-5-a-use-after-free-for-realloc-data)
- [In ssh-agent in OpenSSH before 10.5, some operations can occur remotely but were intended to occur only locally…](https://junglewise.ai/threats/cve-2026-73281-in-ssh-agent-in-openssh-before-10-5-some-operations-can-occur)
- [OpenSSH use-after-free in ssh client during key re-exchange](https://junglewise.ai/threats/cve-2026-60002-openssh-use-after-free-in-ssh-client-during-key-re-exchange)