CVE-2026-55653
Medium
Description
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).
SeverityMedium
CVSS4.3
Exploit probability—
Product
Openbsd Openssh
PublishedJun 23, 2026
First seenJun 23, 2026
Weakness typeCWE-415CWE-415
How to fix
Vendor advisories
- access.redhat.com/security/cve/CVE-2026-55653
- bugzilla.redhat.com/show_bug.cgi?id=2462351
- access.redhat.com/errata/RHSA-2026:36759
- access.redhat.com/errata/RHSA-2026:47755
- access.redhat.com/errata/RHSA-2026:47756
- access.redhat.com/errata/RHSA-2026:47757
- access.redhat.com/errata/RHSA-2026:54387
- access.redhat.com/errata/RHSA-2026:58981
- access.redhat.com/errata/RHSA-2026:76748
- access.redhat.com/errata/RHSA-2026:76993
- access.redhat.com/errata/RHSA-2026:80513
- access.redhat.com/errata/RHSA-2026:82749
Affected products
| Product | Affected versions | Fixed in |
|---|---|---|
| openbsd openssh | No range specified | — |
| redhat hardened_images | No range specified | — |
| redhat openshift_container_platform | 4.0 | — |
| redhat enterprise_linux | 6.0, 7.0, 8.0, 9.0, 10.0 | — |
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