CVE-2026-55653
Published: June 24, 2026Last modified: July 15, 2026
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).
Severity score breakdown
| Parameter | Value |
|---|---|
| Base score | 6.5 |
| Attack Vector | NETWORK |
| Attack complexity | LOW |
| Privileges required | NONE |
| User interaction | REQUIRED |
| Scope | UNCHANGED |
| Confidentiality | NONE |
| Integrity impact | NONE |
| Availability impact | HIGH |
| Vector | CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:N/A:H |
Status
| Product | Release | Package | Status |
|---|---|---|---|
| Alpaquita Linux | 23 LTS | openssh | Not affected (9.1_p1-r3) |
| 25 LTS | openssh | Not affected (10.0_p1-r7) | |
| Stream | openssh | Not affected (9.3_p1-r7) | |
| Hardened Containers | 23 LTS | openssh | Not affected (9.1_p1-r3) |
| 25 LTS | openssh | Not affected (10.0_p1-r7) | |
| Stream | openssh | Not affected (9.3_p1-r7) |