Answer in brief
CVE-2026-55653 records a Medium severity (CVSS 4.3) vulnerability in Openssh: double free in red hat enterprise linux versions of openssh dh-gex client path during fips known-group validation leads to client-side denial of service. The current sources do not mark it as known exploited. The current feed maps Red Hat/openshift/ose-rhel-coreos-8 (generic), Red Hat/openshift/ose-rhel-coreos-9 (generic), 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 4.3. 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/openshift/ose-rhel-coreos-8 (generic), Red Hat/openshift/ose-rhel-coreos-9 (generic), 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:a:redhat:hardened_images:-:*:*:*:*:*:*:* | Not reported | Not reported |
| cpe:2.3:a:redhat:openshift_container_platform:4.0:*:*:*:*:*:*:* | 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/openshift/ose-rhel-coreos-8generic | * | Not reported |
| Red Hat/openshift/ose-rhel-coreos-9generic | * | Not reported |
| 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 malicious SSH server can exploit a double free vulnerability in the Diffie-Hellman Group Exchange (DH-GEX) client path. This occurs during FIPS (Federal Information Processing Standards) mode known-group validation when the client processes attacker-controlled DH-GEX group parameters. Successful exploitation leads to client-side process termination, resulting in a Denial of Service (DoS).
Quoted source text, attributed separately from HOL analysis.