Improper access control in OpenSSH - CVE-2026-35387

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Main Vulnerability Database Vulnerabilities #VU128476

Improper access control in OpenSSH - CVE-2026-35387

Published: April 29, 2026


Vulnerability identifier: #VU128476
CSH Severity: Low
CVSS v4: 7.1 [CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:N/VI:H/VA:N/SC:N/SI:N/SA:N]
CVE-ID: CVE-2026-35387
CWE-ID: CWE-284
Exploitation vector: Remote access
Exploit availability: No public exploit available

Vulnerability details

The vulnerability allows a remote user to bypass configured public key algorithm restrictions.

The vulnerability exists due to improper access control in sshd(8) when applying PubkeyAcceptedAlgorithms and HostbasedAcceptedAlgorithms to ECDSA keys. A remote user can authenticate using an unlisted ECDSA algorithm to bypass configured public key algorithm restrictions.

The issue occurs when one of these directives includes any ECDSA algorithm name.


Affected software

OpenSSH
IBM i
Red Hat Enterprise Linux for x86_64
Anolis OS
Red Hat Enterprise Linux for ARM 64
Red Hat Enterprise Linux for Power, little endian
Red Hat Enterprise Linux for IBM z Systems
Red Hat Enterprise Linux Server - AUS
Red Hat Enterprise Linux Server - TUS
Red Hat Enterprise Linux for ARM 64 - Extended Update Support
Red Hat Enterprise Linux for Power, little endian - Extended Update Support
Red Hat Enterprise Linux for IBM z Systems - Extended Update Support
Red Hat Enterprise Linux for x86_64 - Extended Update Support
openEuler
Ubuntu
Fedora
Red Hat Enterprise Linux Server for Power LE - Update Services for SAP Solutions
pam_ssh_agent_auth
openssh (Red Hat package)
openssh-server
openssh-ldap
openssh-keycat
openssh-clients
openssh-cavs
openssh-askpass
openssh
openssh (Ubuntu package)
openssh-sk-dummy
openssh-doc
openssh-help
openssh-debuginfo
openssh-debugsource

How to mitigate CVE-2026-35387

Install security update from vendor's website.

OpenSSH - update to 10.3p1
pam_ssh_agent_auth - update to 0.10.3-7.29.0.1
pam_ssh_agent_auth - update to 0.10.4-5.13
openssh (Red Hat package) - addressed in versions 8.0p1-7.el8_4.2, 8.0p1-15.el8_6.5, 8.0p1-20.el8_8.4, 8.0p1-29.el8_10, 8.7p1-30.el9_2.11, 8.7p1-45.el9_6.3, 8.7p1-49.el9_7, 9.9p1-7.el10_0.3, 9.9p1-14.el10_1
openssh-server - addressed in versions 8.0p1-29.0.1, 9.6p1-9
openssh-ldap - update to 8.0p1-29.0.1
openssh-keycat - addressed in versions 8.0p1-29.0.1, 9.6p1-9
openssh-clients - addressed in versions 8.0p1-29.0.1, 9.6p1-9
openssh-cavs - update to 8.0p1-29.0.1
openssh-askpass - addressed in versions 8.0p1-29.0.1, 9.6p1-9
openssh - addressed in versions 8.0p1-29.0.1, 9.6p1-9
openssh (Ubuntu package) - addressed in versions 1:8.9p1-3ubuntu0.15, 1:9.6p1-3ubuntu13.16, 1:10.0p1-5ubuntu5.4, 1:10.2p1-2ubuntu3.2
openssh-sk-dummy - update to 9.6p1-9
openssh-doc - update to 9.6p1-9
openssh - update to 9.6p1-13
openssh-help - update to 9.6p1-13
openssh-askpass - update to 9.6p1-13
openssh-clients - update to 9.6p1-13
openssh-debuginfo - update to 9.6p1-13
openssh-debugsource - update to 9.6p1-13
openssh-keycat - update to 9.6p1-13
openssh-server - update to 9.6p1-13
openssh - addressed in versions 10.0p1-9.fc43, 10.2p1-8.fc44

External References

Related Security Bulletins