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Vulnerability · Published Jun 23, 2026 · Assigned by redhat

CVE-2026-55655Openssh: local mitm of x11 forwarding via abstract unix socket pre-binding in red hat enterprise linux openssh client versions

Medium 5.0

In plain English

A medium-severity security flaw in Red Hat Enterprise Linux 10 from Red Hat. There are no confirmed reports of exploitation so far. The chance it is exploited in the next 30 days is estimated at 0.1% (higher than 2% of all known vulnerabilities). Fixed versions are available - upgrade the affected package.

Severity (CVSS 3.1)5.0Medium
Exploit odds (30 days)0.1%top 97.9% of all CVEs
Exploited in the wildNo reportsCISA SSVC: none
Attack toolingNoneno public tooling known

Official description

A flaw was found in OpenSSH. A local unprivileged attacker on a Linux client host can hijack client-side X11 forwarding connections. This is possible by pre-binding the preferred abstract X socket name when X11 forwarding is enabled and a local UNIX-domain X socket is used. A successful attack can compromise the confidentiality of forwarded X11 traffic, including sensitive window contents and input, and may allow some manipulation of the forwarded session.

Affected packages & fixed versions

EcosystemPackageFixed inAdvisory
AlmaLinux:10openssh9.9p1-25.el10_2.alma.1ALSA-2026:47757
AlmaLinux:8openssh8.0p1-30.el8_10ALSA-2026:47755
AlmaLinux:9openssh9.9p1-9.el9_8.alma.1ALSA-2026:47756
AlmaLinux:10openssh-askpass9.9p1-25.el10_2.alma.1ALSA-2026:47757
AlmaLinux:8openssh-askpass8.0p1-30.el8_10ALSA-2026:47755
AlmaLinux:9openssh-askpass9.9p1-9.el9_8.alma.1ALSA-2026:47756
AlmaLinux:8openssh-cavs8.0p1-30.el8_10ALSA-2026:47755
AlmaLinux:10openssh-clients9.9p1-25.el10_2.alma.1ALSA-2026:47757
AlmaLinux:8openssh-clients8.0p1-30.el8_10ALSA-2026:47755
AlmaLinux:9openssh-clients9.9p1-9.el9_8.alma.1ALSA-2026:47756
AlmaLinux:10openssh-keycat9.9p1-25.el10_2.alma.1ALSA-2026:47757
AlmaLinux:8openssh-keycat8.0p1-30.el8_10ALSA-2026:47755
AlmaLinux:9openssh-keycat9.9p1-9.el9_8.alma.1ALSA-2026:47756
AlmaLinux:10openssh-keysign9.9p1-25.el10_2.alma.1ALSA-2026:47757
AlmaLinux:8openssh-ldap8.0p1-30.el8_10ALSA-2026:47755
AlmaLinux:10openssh-server9.9p1-25.el10_2.alma.1ALSA-2026:47757
AlmaLinux:8openssh-server8.0p1-30.el8_10ALSA-2026:47755
AlmaLinux:9openssh-server9.9p1-9.el9_8.alma.1ALSA-2026:47756
AlmaLinux:8pam_ssh_agent_auth0.10.3-7.30.el8_10ALSA-2026:47755
AlmaLinux:9pam_ssh_agent_auth0.10.4-7.9.el9_8.alma.1ALSA-2026:47756
Debian:12opensshno fix listedDEBIAN-CVE-2026-55655
Debian:13opensshno fix listedDEBIAN-CVE-2026-55655
Debian:14opensshno fix listedDEBIAN-CVE-2026-55655
Rocky Linux:10openssh0:9.9p1-25.el10_2.rocky.0.1RLSA-2026:47757
Rocky Linux:8openssh0:8.0p1-30.el8_10RLSA-2026:47755
Rocky Linux:9openssh0:9.9p1-9.el9_8.rocky.0.1RLSA-2026:47756
Ubuntu:25.10opensshno fix listedUBUNTU-CVE-2026-55655
Ubuntu:22.04:LTSopenssh-ssh1no fix listedUBUNTU-CVE-2026-55655
Ubuntu:24.04:LTSopenssh-ssh1no fix listedUBUNTU-CVE-2026-55655
Ubuntu:25.10openssh-ssh1no fix listedUBUNTU-CVE-2026-55655
Ubuntu:26.04:LTSopenssh-ssh1no fix listedUBUNTU-CVE-2026-55655
Ubuntu:26.10openssh-ssh1no fix listedUBUNTU-CVE-2026-55655

Affected products (as reported)

VendorProductVersions
Red Hat Red Hat Enterprise Linux 10 see references
Red Hat Red Hat Enterprise Linux 10.0 Extended Update Support see references
Red Hat Red Hat Enterprise Linux 8 see references
Red Hat Red Hat Enterprise Linux 8 see references
Red Hat Red Hat Enterprise Linux 9 see references
Red Hat Red Hat Enterprise Linux 9 see references
Red Hat Red Hat Enterprise Linux 9.2 Update Services for SAP Solutions see references
Red Hat Red Hat Enterprise Linux 9.4 Update Services for SAP Solutions see references
Red Hat Red Hat Enterprise Linux 9.6 Extended Update Support see references
Red Hat Red Hat Hardened Images see references
Red Hat Red Hat OpenShift AI 3.0 see references
Red Hat Red Hat OpenShift AI 3.0 see references
Red Hat Red Hat OpenShift AI 3.0 see references
Red Hat Red Hat OpenShift AI 3.0 see references
Red Hat Red Hat OpenShift AI 3.0 see references
Red Hat Red Hat OpenShift AI 3.0 see references
Red Hat Red Hat OpenShift AI 3.2 see references
Red Hat Red Hat OpenShift AI 3.2 see references
Red Hat Red Hat OpenShift AI 3.2 see references
Red Hat Red Hat OpenShift AI 3.2 see references
Red Hat Red Hat OpenShift AI 3.2 see references
Red Hat Red Hat OpenShift AI 3.2 see references
Red Hat Red Hat OpenShift AI 3.3 see references
Red Hat Red Hat OpenShift AI 3.3 see references
Red Hat Red Hat OpenShift AI 3.3 see references
Red Hat Red Hat OpenShift AI 3.3 see references
Red Hat Red Hat OpenShift AI 3.3 see references
Red Hat Red Hat OpenShift AI 3.3 see references
Red Hat Red Hat OpenShift AI 3.3 see references
Red Hat Red Hat OpenShift AI 3.3 see references

Weakness: CWE-923 · Vector: CVSS:3.1/AV:L/AC:H/PR:L/UI:R/S:U/C:H/I:L/A:N

References