Improper Authorization in OpenSSH - CVE-2026-35388

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Main Vulnerability Database Vulnerabilities #VU128477

Improper Authorization in OpenSSH - CVE-2026-35388

Published: April 29, 2026


Vulnerability identifier: #VU128477
CSH Severity: Low
CVSS v4: 4.8 [CVSS:4.0/AV:L/AC:L/AT:N/PR:L/UI:N/VC:L/VI:L/VA:N/SC:N/SI:N/SA:N]
CVE-ID: CVE-2026-35388
CWE-ID: CWE-285
Exploitation vector: Local access
Exploit availability: No public exploit available

Vulnerability details

The vulnerability allows a local user to bypass connection multiplexing confirmation.

The vulnerability exists due to improper access control in ssh(1) when handling proxy mode multiplexing sessions requested with ssh -O proxy under ControlMaster ask or autoask. A local user can initiate a proxy mode multiplexing session to bypass connection multiplexing confirmation.

The issue is limited to proxy mode multiplexing sessions.


Affected software

OpenSSH
SUSE Linux Enterprise Server 15 SP6
SUSE Linux Enterprise Server 12 SP5 LTSS Extended
SUSE Linux Enterprise Server 12 SP5
SUSE Linux Enterprise Server 15 SP5
SUSE Linux Enterprise Server 15 SP4
SUSE Linux Enterprise High Performance Computing 15
SUSE Linux Enterprise High Performance Computing ESPOS 15
SUSE Linux Enterprise Server for SAP Applications 15
SUSE Linux Enterprise Server 15
SUSE Linux Enterprise High Performance Computing LTSS 15
SUSE Linux Enterprise Server for SAP Applications 12
SUSE Linux Enterprise High Performance Computing 12
SUSE Linux Enterprise Server 12
SUSE Linux Enterprise Real Time 15
SUSE Linux Enterprise Desktop 15
SUSE Linux Enterprise Micro for Rancher
SUSE Linux Enterprise Micro
IBM i
Red Hat Enterprise Linux for Power, little endian
Anolis OS
Red Hat Enterprise Linux for ARM 64
Red Hat Enterprise Linux for IBM z Systems
Red Hat Enterprise Linux for x86_64
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
Desktop Applications Module
Basesystem Module
openSUSE Leap
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
openssh-askpass
openssh-cavs
openssh-server
openssh-ldap
openssh-keycat
openssh-clients
openssh8.4-fips
openssh8.4-common-debuginfo
openssh8.4-debugsource
openssh8.4-clients
openssh8.4
openssh8.4-server
openssh8.4-helpers-debuginfo
openssh8.4-common
openssh8.4-clients-debuginfo
openssh8.4-server-debuginfo
openssh8.4-helpers
openssh-askpass-gnome-debuginfo
openssh-fips
openssh-helpers-debuginfo
openssh-debugsource
openssh-clients-debuginfo
openssh-debuginfo
openssh-askpass-gnome-debugsource
openssh-server-debuginfo
openssh-helpers
openssh-askpass-gnome
openssh-common-debuginfo
openssh-common
openssh-cavs-debuginfo
openssh (Ubuntu package)
openssh-sk-dummy
openssh-doc
openssh-help
openssh-server-config-disallow-rootlogin

How to mitigate CVE-2026-35388

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 - addressed in versions 8.0p1-29.0.1, 9.6p1-6
openssh-askpass - addressed in versions 8.0p1-29.0.1, 9.6p1-6
openssh-cavs - update to 8.0p1-29.0.1
openssh-server - addressed in versions 8.0p1-29.0.1, 9.6p1-6
openssh-ldap - update to 8.0p1-29.0.1
openssh-keycat - addressed in versions 8.0p1-29.0.1, 9.6p1-6
openssh-clients - addressed in versions 8.0p1-29.0.1, 9.6p1-6
openssh8.4-fips - update to 8.4p1-8.24.1
openssh8.4-common-debuginfo - update to 8.4p1-8.24.1
openssh8.4-debugsource - update to 8.4p1-8.24.1
openssh8.4-clients - update to 8.4p1-8.24.1
openssh8.4 - update to 8.4p1-8.24.1
openssh8.4-server - update to 8.4p1-8.24.1
openssh8.4-helpers-debuginfo - update to 8.4p1-8.24.1
openssh8.4-common - update to 8.4p1-8.24.1
openssh8.4-clients-debuginfo - update to 8.4p1-8.24.1
openssh8.4-server-debuginfo - update to 8.4p1-8.24.1
openssh8.4-helpers - update to 8.4p1-8.24.1
openssh-askpass-gnome-debuginfo - addressed in versions 8.4p1-150300.3.65.1, 9.6p1-150600.6.42.1
openssh-fips - addressed in versions 8.4p1-150300.3.65.1, 9.6p1-150600.6.42.1
openssh-server - addressed in versions 8.4p1-150300.3.65.1, 9.6p1-150600.6.42.1
openssh - addressed in versions 8.4p1-150300.3.65.1, 9.6p1-150600.6.42.1
openssh-helpers-debuginfo - addressed in versions 8.4p1-150300.3.65.1, 9.6p1-150600.6.42.1
openssh-clients - addressed in versions 8.4p1-150300.3.65.1, 9.6p1-150600.6.42.1
openssh-debugsource - addressed in versions 8.4p1-150300.3.65.1, 9.6p1-150600.6.42.1
openssh-cavs - addressed in versions 8.4p1-150300.3.65.1, 9.6p1-150600.6.42.1
openssh-clients-debuginfo - addressed in versions 8.4p1-150300.3.65.1, 9.6p1-150600.6.42.1
openssh-debuginfo - addressed in versions 8.4p1-150300.3.65.1, 9.6p1-150600.6.42.1
openssh-askpass-gnome-debugsource - addressed in versions 8.4p1-150300.3.65.1, 9.6p1-150600.6.42.1
openssh-server-debuginfo - addressed in versions 8.4p1-150300.3.65.1, 9.6p1-150600.6.42.1
openssh-helpers - addressed in versions 8.4p1-150300.3.65.1, 9.6p1-150600.6.42.1
openssh-askpass-gnome - addressed in versions 8.4p1-150300.3.65.1, 9.6p1-150600.6.42.1
openssh-common-debuginfo - addressed in versions 8.4p1-150300.3.65.1, 9.6p1-150600.6.42.1
openssh-common - addressed in versions 8.4p1-150300.3.65.1, 9.6p1-150600.6.42.1
openssh-cavs-debuginfo - addressed in versions 8.4p1-150300.3.65.1, 9.6p1-150600.6.42.1
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 9.6p1-6
openssh-doc - update to 9.6p1-6
openssh-debugsource - update to 9.6p1-13
openssh-keycat - update to 9.6p1-13
openssh-server - update to 9.6p1-13
openssh-help - update to 9.6p1-13
openssh-debuginfo - update to 9.6p1-13
openssh-clients - update to 9.6p1-13
openssh-askpass - update to 9.6p1-13
openssh - update to 9.6p1-13
openssh-server-config-disallow-rootlogin - update to 9.6p1-150600.6.42.1
openssh - addressed in versions 10.0p1-9.fc43, 10.2p1-8.fc44

External References

Related Security Bulletins