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    CVE-2026-55653

    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).

    Published:Jun 22, 2026
    Last Modified:Aug 25, 2026
    EPS:Jun 23, 2026
    EPSS Score:0.0029
    CVSS Score:4.3

    Affected Products

    Vendor
    Openbsd
    Product
    Openssh
    Vendor
    Openssh
    Product
    Openssh
    Vendor
    Redhat
    Product
    Enterprise Linux
    Vendor
    Redhat
    Product
    Hardened Images
    Vendor
    Redhat
    Product
    Hummingbird
    Vendor
    Redhat
    Product
    Openshift
    Vendor
    Redhat
    Product
    Openshift Container Platform
    Vendor
    Redhat
    Product
    Rhui

    Exploits

    https://bugzilla.redhat.com/show_bug.cgi?id=2462351

    Common Weakness Enumeration

    CWE-415 Double Free

    Common Attack Pattern Enumeration and Classification (CAPEC)

    No CAPEC recorded yet

    Related CVEs

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    CVE-2026-73281 (CVSS 3.5) — In ssh-agent in OpenSSH before 10.5, some operations can occur remotely but were intended to occur only locall…
    CVE-2026-60002 (CVSS 7.7) — ssh in OpenSSH before 10.4 can have a use-after-free when a server changes its host key during a key re-exchan…
    CVE-2026-60001 (CVSS 6.5) — sshd in OpenSSH before 10.4 does not always honor the minimum authentication delay.…
    CVE-2026-60000 (CVSS 3.7) — sshd in OpenSSH before 10.4 allows remote attackers to cause a denial of service (resource consumption from ex…
    CVE-2026-59999 (CVSS 5.9) — In sshd in OpenSSH before 10.4, DisableForwarding=yes was supposed to take precedence over PermitTunnel=yes, b…
    CVE-2026-59998 (CVSS 4.8) — sshd in OpenSSH before 10.4 has an undocumented security-relevant behavior: GSSAPIStrictAcceptorCheck has no v…
    CVE-2026-59997 (CVSS 4.2) — internal-sftp in sshd in OpenSSH before 10.4 recognizes only the first 9 command-line arguments, which can be …
    CVE-2026-59996 (CVSS 4.2) — scp in OpenSSH before 10.4 may place a file in the parent directory of an intended directory when the copy occ…

    Common Vulnerability Scoring System

    Attack Vector
    Network
    Adjacent
    Local
    Physical
    Privileges Required
    None
    Low
    High
    User Interaction
    None
    Required
    Scope
    Unchanged
    Changed
    Confidentiality
    None
    Low
    High
    Integrity
    None
    Low
    High
    Availability
    None
    Low
    High