Answer in brief
CVE-2026-55655 records a Medium severity (CVSS 5.0) vulnerability in Openssh: local mitm of x11 forwarding via abstract unix socket pre-binding in red hat enterprise linux openssh client versions. The current sources do not mark it as known exploited. The current feed maps Red Hat/openssh (generic). Check affected ranges and fixed versions before updating.
Analysis pending evidence review
HOL Guard separates source facts from reviewed analysis. See the methodology.
CVSS is 5.0. The current sources do not mark it as known exploited. Treat this as a source-backed prioritization signal, not a statement about your environment.
Analysis status
Analysis pending evidence review
Factual feed record only; HOL analysis is not approved for indexing. Read the methodology.
The current feed maps Red Hat/openssh (generic). Check affected ranges and fixed versions before updating.
| Product | Affected versions | Fixed versions |
|---|---|---|
| cpe:2.3:a:openbsd:openssh:-:*:*:*:*:*:*:* | Not reported | Not reported |
| cpe:2.3:o:redhat:enterprise_linux:10.0:*:*:*:*:*:*:* | Not reported | Not reported |
| cpe:2.3:o:redhat:enterprise_linux:6.0:*:*:*:*:*:*:* | Not reported | Not reported |
| cpe:2.3:o:redhat:enterprise_linux:7.0:*:*:*:*:*:*:* | Not reported | Not reported |
| cpe:2.3:o:redhat:enterprise_linux:8.0:*:*:*:*:*:*:* | Not reported | Not reported |
| cpe:2.3:o:redhat:enterprise_linux:9.0:*:*:*:*:*:*:* | Not reported | Not reported |
| Package | Affected range | Fixed version |
|---|---|---|
| Red Hat/opensshgeneric | * | Not reported |
Published upstream
Jun 23, 2026
Evidence: source:cvelist:source_dates:source-dates:recordSource modified
Sep 1, 2026
Evidence: source:cvelist:source_dates:source-dates:recordFirst seen by HOL
Jun 23, 2026
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.
Quoted source text, attributed separately from HOL analysis.