CVE-2026-59999
Official description Straight from the sourceThe vendor's or NVD's own wording, published unedited. Authoritative, but often terse — it says what broke, rarely what to do.
NVD · uneditedIn sshd in OpenSSH before 10.4, DisableForwarding=yes was supposed to take precedence over PermitTunnel=yes, but did not.
In the news
Third-party coverageSurfaced from public web coverage — external links open in a new tab.
Technical summary Written by usOur analysis, written from the advisory, the CVSS vector and the affected-version data. It adds context the advisory leaves out, and never invents facts that are not in the source.
dbcve analysis · high confidenceIn sshd in OpenSSH before 10.4, the configuration directive DisableForwarding=yes was not properly enforced when PermitTunnel=yes was also set, allowing tunnel forwarding to remain active despite explicit configuration to disable it. This represents an authorization bypass where security settings did not behave as documented.
Verify against the referenced sources before acting — the references below are authoritative for this CVE, this summary is not.
Affected products & versions What the vendor confirmedThe version ranges the vendor confirmed as vulnerable. If your version sits inside a range here, treat yourself as exposed until you have upgraded.
NVD · CPE data< 10.4CVSS breakdown How the score is builtThe industry scoring standard. It rates how the flaw is reached, what it takes to exploit, and what an attacker gains — the score is derived from those, not the other way round.
From the vector- Attack vector
- Network
- Complexity
- Low
- Privileges
- None
- User interaction
- None
- Scope
- Unchanged
- Confidentiality
- None
- Integrity
- High
- Availability
- None
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N
Am I affected? How to checkSteps we derive from the advisory and the affected-version data, so you can decide whether this CVE reaches your setup. They are a guide, not a scan — your own configuration is the authority.
dbcve checksWork through these to decide whether this CVE applies to you.
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Check OpenSSH versionRun 'sshd -V' or 'ssh -V' to obtain the version numberAffected if The version is less than 10.4 on OpenBSD-based OpenSSH
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Locate sshd configuration fileFind the sshd_config file, typically at /etc/ssh/sshd_config or /etc/sshd_configAffected if Unable to locate the configuration file for inspection
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Check for DisableForwarding directiveSearch the sshd_config file for 'DisableForwarding' and note its valueAffected if DisableForwarding=yes is set in the configuration
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Check for PermitTunnel directiveSearch the sshd_config file for 'PermitTunnel' and note its valueAffected if PermitTunnel=yes is set in the configuration
A system is affected if it runs OpenSSH versions prior to 10.4 on OpenBSD and has both DisableForwarding=yes and PermitTunnel=yes configured simultaneously, as the DisableForwarding setting would be bypassed.
Generated from the published advisory. Verify against your own configuration.
Remediation Closing itWhat it takes to close this. Where a vendor fix exists we point at it; where none exists we say so plainly, and can build one. Effort estimates are scoped from the advisory, not from your codebase.
dbcve · scoped10.4
Upgrade OpenSSH to version 10.4 or later to receive the upstream fix. After upgrading, verify that DisableForwarding=yes properly takes precedence over PermitTunnel=yes by testing that no tunnel forwarding can be established.
OpenSSH 10.4
- 1. Check current OpenSSH version: sshd -V or ssh -V
- 2. Plan maintenance window for the upgrade
- 3. Backup current sshd configuration: cp /etc/ssh/sshd_config /etc/ssh/sshd_config.backup
- 4. Upgrade OpenSSH to version 10.4 or later using your system's package manager (e.g., apt-get update && apt-get install openssh-server, yum update openssh-server, or apk upgrade openssh)
- 5. Verify new version: sshd -V
- 6. Test SSH connectivity with a backup session before closing existing connections
- 7. Restart sshd service: systemctl restart sshd or service ssh restart
Generated from the published advisory — verify against the referenced sources before acting.
- Consultation3.0 h
- Implementation4.0 h
- Testing3.0 h
- Review / QA2.0 h
An estimate, not a bill — we confirm scope with you before any work starts. Need it this week? Rush from $3,408.
Scan for this in your stack
Free · runs locallyCheck whether your project pulls in CVE-2026-59999 — or any other known-vulnerable package — straight from your lock files. Free and open source; it runs locally and uploads nothing.
References Go to the primary sourcePrimary sources — vendor advisories, patches and trackers. Where our summary and a reference disagree, the reference wins.
Primary sourcesPractitioner notes
ContributedPeer-ranked notes from engineers who’ve handled CVE-2026-59999 in production — separate from our analysis above.
The advisory tells you what broke. It rarely tells you what actually worked. If you’ve dealt with this one, that detail is what the next engineer is searching for.
- The version that genuinely resolved it — not the one the vendor claimed
- A config change or rule that shut the vector down
- A gotcha in the upgrade path that cost you an afternoon
No notes yet
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- Verified mitigations, workarounds, and config changes
- Version or environment caveats, and links to real fixes
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