Medium5.0Red Hat Linux Updated
Local MITM of X11 forwarding via abstract UNIX socket pre-binding in Red Hat Enterprise Linux OpenSSH client versions
CVE-2026-55655 Published Jun 22, 2026Updated by vendor Jun 22, 2026
Affected products & platforms
Red Hat LinuxUnclassified
Summary
Local MITM of X11 forwarding via abstract UNIX socket pre-binding in Red Hat Enterprise Linux OpenSSH client versions. Red Hat rates this moderate (CVSS 5). Weakness: CWE-923. Red Hat lists fixing advisory RHSA-2026:36759 with package openssh-main-10.3p1-6.hum1.
Fixed versions
- openssh-main-10.3p1-6.hum1
- RHSA-2026:36759
Official advisory · high-confidence parse· fetched 7 hours ago·verify at source
Mitigation checklist
Recommended fix / mitigation
- To mitigate this issue, disable X11 forwarding on OpenSSH clients when it is not required. This can be achieved by avoiding the use of `-X` or `-Y` options when invoking `ssh`, or by setting `ForwardX11 no` in the SSH client configuration file (`~/.ssh/config` or `/etc/ssh/ssh_config`). Disabling X11 forwarding will prevent the client from attempting to establish X11 connections, thereby removing the attack vector.
Official advisory · high-confidence parse· fetched 7 hours ago·verify at source
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