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    CVE-2016-8858

    The kex_input_kexinit function in kex.c in OpenSSH 6.x and 7.x through 7.3 allows remote attackers to cause a denial of service (memory consumption) by sending many duplicate KEXINIT requests. NOTE: a third party reports that "OpenSSH upstream does not consider this as a security issue."

    Published:Oct 17, 2016
    Last Modified:May 29, 2026
    EPS:Dec 9, 2016
    EPSS Score:0.26866
    CVSS Score:7.5

    Affected Products

    Vendor
    Openbsd
    Product
    Openssh

    Exploits

    https://github.com/dag-erling/kexkill

    Related CVEs

    CVE-2026-73283 (CVSS 2.5) — In sshd in OpenSSH before 10.5, the restrict keyword (in authorized_keys) was supposed to be applicable to tun…
    CVE-2026-73282 (CVSS 4.8) — In ssh in OpenSSH before 10.5, a use-after-free for realloc data can occur if a certain pair of remote-forward…
    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…

    References

    http://cvsweb.openbsd.org/cgi-bin/cvsweb/src/usr.bin/ssh/kex.c.diff?r1=1.126&r2=1.127&f=h
    http://cvsweb.openbsd.org/cgi-bin/cvsweb/src/usr.bin/ssh/kex.c?rev=1.127&content-type=text/x-cvsweb-markup
    http://www.openwall.com/lists/oss-security/2016/10/19/3
    http://www.openwall.com/lists/oss-security/2016/10/20/1
    http://www.securityfocus.com/bid/93776
    http://www.securitytracker.com/id/1037057
    https://bugzilla.redhat.com/show_bug.cgi?id=1384860
    https://cert-portal.siemens.com/productcert/pdf/ssa-412672.pdf
    https://ftp.openbsd.org/pub/OpenBSD/patches/6.0/common/013_ssh_kexinit.patch.sig
    https://github.com/openssh/openssh-portable/commit/ec165c392ca54317dbe3064a8c200de6531e89ad
    https://security.FreeBSD.org/advisories/FreeBSD-SA-16:33.openssh.asc
    https://security.gentoo.org/glsa/201612-18
    https://security.netapp.com/advisory/ntap-20180201-0001/
    http://cvsweb.openbsd.org/cgi-bin/cvsweb/src/usr.bin/ssh/kex.c.diff?r1=1.126&r2=1.127&f=h
    http://cvsweb.openbsd.org/cgi-bin/cvsweb/src/usr.bin/ssh/kex.c?rev=1.127&content-type=text/x-cvsweb-markup
    http://www.openwall.com/lists/oss-security/2016/10/19/3
    http://www.openwall.com/lists/oss-security/2016/10/20/1
    http://www.securityfocus.com/bid/93776
    http://www.securitytracker.com/id/1037057
    https://bugzilla.redhat.com/show_bug.cgi?id=1384860
    https://cert-portal.siemens.com/productcert/pdf/ssa-412672.pdf
    https://ftp.openbsd.org/pub/OpenBSD/patches/6.0/common/013_ssh_kexinit.patch.sig
    https://github.com/openssh/openssh-portable/commit/ec165c392ca54317dbe3064a8c200de6531e89ad
    https://security.FreeBSD.org/advisories/FreeBSD-SA-16:33.openssh.asc
    https://security.gentoo.org/glsa/201612-18
    https://security.netapp.com/advisory/ntap-20180201-0001/

    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