CVE-2026-59999Network attack vector

Authenticated tunnel creation via configuration precedence bypass

Published Jul 8, 2026 · Updated Jul 8, 2026

Improper configuration precedence in OpenSSH sshd before 10.4 allows remote authenticated users to create network tunnels. The server's tunnel-request path honored PermitTunnel=yes without enforcing the documented DisableForwarding override. Exploitation requires both conflicting settings and usable tunnel devices; it bypasses the administrator's forwarding restriction and permits network traffic routing.

CVSS severity5.9
Medium
EPSS probability0.16%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Improper configuration precedence in OpenSSH sshd before 10.4 allows remote authenticated users to create network tunnels. The server's tunnel-request path honored PermitTunnel=yes without enforcing the documented DisableForwarding override. Exploitation requires both conflicting settings and usable tunnel devices; it bypasses the administrator's forwarding restriction and permits network traffic routing.

The record

CVE
CVE-2026-59999
Published
Jul 8, 2026
Updated
Jul 8, 2026
Vendor
OpenBSD Project
Product
OpenSSH
Classifications
CWE-348, T1572
Attack vector
network
Privileges
authenticated

Timeline

How it unfolded

  1. Jul 8, 2026CVE publishedPublication date reported by the CVE source.
  2. Jul 8, 2026Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=0 <10.4

What conditions does exploitation require?

Attack vectornetwork
Required privilegesauthenticated

What is affected?

OpenBSD Project · OpenSSHversion=0 <10.4

Published CVSS scores

7.5NIST NVDCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N
5.9MITRECVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:H/A:N

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-348Use of Less Trusted Source
T1572Protocol Tunneling

Public exploit references

No public exploit references are available in this record.

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

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Your stack

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