CVE-2026-55655 (GCVE-0-2026-55655)

Vulnerability from cvelistv5 – Published: 2026-06-23 03:36 – Updated: 2026-07-30 08:22
VLAI
Title
Openssh: local mitm of x11 forwarding via abstract unix socket pre-binding in red hat enterprise linux openssh client versions
Summary
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.
Severity
5 (Medium)
CVSS:3.1/AV:L/AC:H/PR:L/UI:R/S:U/C:H/I:L/A:N
SSVC
Exploitation: none Automatable: no Technical Impact: partial
CISA Coordinator (v2.0.3)
CWE
  • CWE-923 - Improper Restriction of Communication Channel to Intended Endpoints
Assigner
References
URL Tags
https://access.redhat.com/errata/RHSA-2026:36759 vendor-advisoryx_refsource_REDHAT
https://access.redhat.com/errata/RHSA-2026:47755 vendor-advisoryx_refsource_REDHAT
https://access.redhat.com/errata/RHSA-2026:47756 vendor-advisoryx_refsource_REDHAT
https://access.redhat.com/errata/RHSA-2026:47757 vendor-advisoryx_refsource_REDHAT
https://access.redhat.com/security/cve/CVE-2026-55655 vdb-entryx_refsource_REDHAT
https://bugzilla.redhat.com/show_bug.cgi?id=2462250 issue-trackingx_refsource_REDHAT
Impacted products
Vendor Product Version
Red Hat Red Hat Enterprise Linux 10 Unaffected: 0:9.9p1-25.el10_2 , < * (rpm)
    cpe:/o:redhat:enterprise_linux:10.2
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Red Hat Red Hat Enterprise Linux 8 Unaffected: 0:8.0p1-30.el8_10 , < * (rpm)
    cpe:/a:redhat:enterprise_linux:8::appstream
    cpe:/o:redhat:enterprise_linux:8::baseos
 Create a notification for this product.
Red Hat Red Hat Enterprise Linux 9 Unaffected: 0:9.9p1-9.el9_8 , < * (rpm)
    cpe:/a:redhat:enterprise_linux:9::appstream
    cpe:/o:redhat:enterprise_linux:9::baseos
 Create a notification for this product.
Red Hat Red Hat Hardened Images Unaffected: 10.3p1-6.hum1 , < * (rpm)
    cpe:/a:redhat:hummingbird:1
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Red Hat Red Hat Enterprise Linux 6     cpe:/o:redhat:enterprise_linux:6
 Create a notification for this product.
Red Hat Red Hat Enterprise Linux 7     cpe:/o:redhat:enterprise_linux:7
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Red Hat Red Hat OpenShift Container Platform 4     cpe:/a:redhat:openshift:4
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Date Public
2026-06-22 23:22
Show details on NVD website
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\"value\": \"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.\"}], \"x_generator\": {\"engine\": \"cvelib 1.8.0\"}, \"descriptions\": [{\"lang\": \"en\", \"value\": \"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. 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      "cveMetadata": "{\"cveId\": \"CVE-2026-55655\", \"state\": \"PUBLISHED\", \"dateUpdated\": \"2026-07-30T08:22:20.146Z\", \"dateReserved\": \"2026-06-16T23:55:05.737Z\", \"assignerOrgId\": \"53f830b8-0a3f-465b-8143-3b8a9948e749\", \"datePublished\": \"2026-06-23T03:36:25.724Z\", \"assignerShortName\": \"redhat\"}",
      "dataType": "CVE_RECORD",
      "dataVersion": "5.2"
    }
  }
}



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Tags
Taxonomy of the tags.





Forecast uses a logistic model when the trend is rising, or an exponential decay model when the trend is falling. Fitted via linearized least squares.

Sightings

Author Source Type Date Other

Nomenclature

  • Seen: The vulnerability was mentioned, discussed, or observed by the user.
  • Confirmed: The vulnerability has been validated from an analyst's perspective.
  • Published Proof of Concept: A public proof of concept is available for this vulnerability.
  • Exploited: The vulnerability was observed as exploited by the user who reported the sighting.
  • Patched: The vulnerability was observed as successfully patched by the user who reported the sighting.
  • Not exploited: The vulnerability was not observed as exploited by the user who reported the sighting.
  • Not confirmed: The user expressed doubt about the validity of the vulnerability.
  • Not patched: The vulnerability was not observed as successfully patched by the user who reported the sighting.


Detection rules are retrieved from Rulezet.