OpenSSH: Incorrect Behavior Order
CVE-2026-35386 is a high-severity incorrect behavior order vulnerability in OpenSSH from OpenBSD, with a CVSS 3.1 base score of 8.1 out of 10. It can be exploited remotely over the network by an unauthenticated attacker, without any action from a user. The record lists version 10.3 as the first without the flaw, so updating OpenSSH to that release or later removes the exposure. There is no confirmed exploitation so far. EPSS estimates a 0.32% chance of exploitation within 30 days, which is low compared with other CVEs.
High severity with no evidence of exploitation so far.
What to do
- Update OpenSSH to 10.3 or a later version.
- Until you can update, restrict network access to the affected service so it is not reachable from untrusted networks.
Affected products and versions
Version data comes from the organisation that assigned the CVE. Confirm against the vendor advisory before deciding you are unaffected.
How the severity score breaks down
- Attack vector
- NetworkCan be exploited remotely over a network, including the internet.
- Attack complexity
- HighSuccess depends on conditions outside the attacker's control.
- Privileges required
- NoneNo account or login is needed.
- User interaction
- NoneNo action by a victim is required.
- Scope
- UnchangedImpact stays within the vulnerable component.
- Confidentiality
- HighAll data handled by the component can be read.
- Integrity
- HighData or code can be modified at will.
- Availability
- HighThe component can be taken down completely.
Vector: CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H. Scored by NVD.
| Scoring system | Score | Severity | Scored by |
|---|---|---|---|
| CVSS 3.1 | 3.6 | Low | CNA (mitre.org) |
| CVSS 3.1 | 8.1 | High | NVD |
Official description
In OpenSSH before 10.3, command execution can occur via shell metacharacters in a username within a command line. This requires a scenario where the username on the command line is untrusted, and also requires a non-default configurations of % in ssh_config.
Source: the CVE record as published by its numbering authority, via NVD and CVE.org.
The underlying weakness: Incorrect Behavior Order
The product performs multiple related behaviors, but the behaviors are performed in the wrong order in ways that may produce resultant weaknesses.
Timeline
- CVE record published.
- CISA published its SSVC assessment (exploitation: none, automatable: no, technical impact: total).
- Record last changed materially (score, affected products, status or references).
References
Patches and release notes
- openssh.org/releasenotes.html#10.3p1Release Notes
Third-party and government advisories
- marc.info/?l=openssh-unix-dev&m=177513443901484&w=2Third Party Advisory
- openwall.com/lists/oss-security/2026/04/02/3Third Party Advisory
Other vulnerabilities in OpenSSH
- 8.1 High severity
- 9.4 Critical severity
- 7.5 High severity
- 8.1 High severity
- 8.1 High severity
- 7.5 High severity
Recent Incorrect Behavior Order vulnerabilities
- 7.5 High severity
- 7.2 High severity
- 7.2 High severity
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