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OpenSSH CVE-2026-35386

| EUVDEUVD-2026-18400 HIGH
Incorrect Behavior Order (CWE-696)
2026-04-02 cve@mitre.org
High
Disputed · 8.1 NVD
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Severity by source

Sources disagree (Low–High)
NVD PRIMARY
8.1 HIGH
AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H
vuln.today AI
8.1 HIGH

AC:H because exploitation needs both an untrusted username on the command line and a non-default %-expansion ssh_config; PR:N as the attacker only supplies input; full command execution yields C/I/A:H.

3.1 AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H
4.0 AV:N/AC:L/AT:P/PR:N/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N
SUSE
3.6 LOW
AV:L/AC:H/PR:L/UI:N/S:U/C:L/I:L/A:N
Red Hat
3.6 LOW
qualitative

vuln.today treats the vendor’s rating as authoritative. A higher third-party CVSS (e.g. CISA-ADP) is shown for transparency but does not drive the headline severity.

CVSS VectorNVD

Attack Vector
Network
Attack Complexity
High
Privileges Required
None
User Interaction
None
Scope
Unchanged
Confidentiality
High
Integrity
High
Availability
High

Lifecycle Timeline

9
Analysis Updated
Jul 07, 2026 - 16:14 vuln.today
v3 (cvss_changed)
Analysis Updated
Jul 07, 2026 - 16:13 vuln.today
v2 (cvss_changed)
Re-analysis Queued
Jul 07, 2026 - 16:07 vuln.today
cvss_changed
Severity Changed
Jul 07, 2026 - 16:07 NVD
LOW HIGH
CVSS changed
Jul 07, 2026 - 16:07 NVD
3.6 (LOW) 8.1 (HIGH)
Patch available
Apr 16, 2026 - 05:29 EUVD
10.3
EUVD ID Assigned
Apr 02, 2026 - 17:22 euvd
EUVD-2026-18400
Analysis Generated
Apr 02, 2026 - 17:22 vuln.today
CVE Published
Apr 02, 2026 - 17:16 nvd
LOW 3.6

DescriptionNVD

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.

AnalysisAI

Argument/command injection in OpenSSH before 10.3 lets shell metacharacters embedded in an untrusted username trigger command execution on the SSH-client host. It affects deployments that both feed an attacker-influenced username to the ssh command line and use a non-default ssh_config where %-token expansion (e.g. in ProxyCommand/LocalCommand) is enabled. There is no public exploit identified at time of analysis, EPSS is negligible (0.01%), and it is not in CISA KEV; a fixed release (10.3/10.3p1) is available.

Technical ContextAI

OpenSSH is the OpenBSD-maintained SSH client/server suite (CPE cpe:2.3:a:openbsd:openssh) that ships as the default SSH implementation on virtually all Linux/BSD/macOS systems. The ssh_config directives ProxyCommand, LocalCommand and similar support percent-token expansion, where tokens such as %r (remote username) and %u are substituted into a string that is subsequently handed to a shell. CWE-696 (Incorrect Behavior Order) is the root cause: the username value is expanded into the command string before it is properly neutralized, so shell metacharacters in the username survive into shell interpretation. When an application or wrapper passes a username derived from untrusted input to ssh, and the local ssh_config uses these %-tokens, the metacharacters are executed rather than treated as literal text.

RemediationAI

Vendor-released patch: upgrade to OpenSSH 10.3 (portable 10.3p1) or later per the OpenSSH release notes (https://www.openssh.org/releasenotes.html#10.3p1); on Ubuntu apply the packaged fix from USN-8222-1 (https://ubuntu.com/security/notices/USN-8222-1) and equivalent distro updates elsewhere. If immediate patching is not possible, eliminate the trigger conditions: stop passing untrusted or externally-derived usernames directly onto the ssh command line (validate/allowlist usernames to safe characters before invoking ssh), and review ssh_config and ssh_config.d for ProxyCommand, LocalCommand or other directives using %r/%u tokens, removing or hardening them where the username is not fully trusted - the trade-off is loss of the dynamic proxy/local-command behavior those directives provide. These controls address the exact preconditions rather than relying on generic defense in depth.

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Vendor StatusVendor

SUSE

Severity: Low
Product Status
SUSE Liberty Linux 10 Fixed
SUSE Liberty Linux 8 Fixed
SUSE Liberty Linux 9 Fixed
SLES15-SP5-CHOST-BYOS-SAP-CCloud Affected
SLES15-SP6-CHOST-BYOS Affected

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CVE-2026-35386 vulnerability details – vuln.today

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