CVE-2026-59999·OpenSSH vulnerability

How likely is exploitation

FIRST's Exploit Prediction Scoring System puts the probability of this CVE being exploited in the next 30 days at 0.16% — higher than 4% of all published CVEs. EPSS is an independent forecast of exploitation, not a severity rating: it says nothing about how much damage a successful attack does, which is what a CVSS score measures.

Affected versions

How to fix this CVE

Update OpenSSH to version 10.4 or later to ensure that the DisableForwarding directive properly overrides tunnel permissions. This fixes a configuration precedence issue where tunnel forwarding could remain enabled even when explicitly disabled at the server level. Prioritize this update for systems where tunnel access must be restricted for security compliance.

sudo dnf update openssh-server openssh-clients

How to check if you are affected

1. Check installed OpenSSH version: ssh -V
2. Verify your sshd configuration contains DisableForwarding=yes: sudo grep -i 'DisableForwarding\|PermitTunnel' /etc/ssh/sshd_config
3. Review sshd logs for tunnel-related connection attempts: sudo grep -i 'tun\|forward' /var/log/auth.log or /var/log/secure
4. Confirm the fix by verifying OpenSSH version is 10.4p1 or later: ssh -V | grep -E '10\.[4-9]|[1-9][0-9]\.' && echo 'Patched' || echo 'Vulnerable'

FAQ

Related OpenSSH CVEs

References

• https://marc.info/?l=openssh-unix-dev&m=178333966933090&w=2
• https://www.openssh.org/releasenotes.html#10.4p1
• https://www.openwall.com/lists/oss-security/2026/07/06/5