How severe is CVE-2016-8858?

CVE-2016-8858 has a CVSS 3.x base score of 7.5, rated high severity. It is exploitable over network with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is none, integrity none, and availability high.

Is CVE-2016-8858 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 29% (98th percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2016-8858?

CVE-2016-8858 primarily affects Openbsd Openssh. In total, 6 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.

How do I fix CVE-2016-8858?

Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its high severity, prioritise patching exposed systems.

When was CVE-2016-8858 published?

CVE-2016-8858 was published on 2016-12-09 and last updated on 2026-06-17.

CVE-2016-8858

CVE-2016-8858 is a high-severity vulnerability in Openbsd Openssh with a CVSS 3.x base score of 7.5. Its EPSS exploit-prediction score of 29% places it in the 98th percentile, indicating an elevated likelihood of exploitation. The underlying weakness is classified as CWE-399.

Key facts

Severity: High (CVSS 3.x base score 7.5)
CVSS v2: 7.8
EPSS exploit prediction: 29% (98th percentile)
Actively exploited: Not listed in CISA KEV
Weakness: CWE-399
Affected product: Openbsd Openssh
Published: 2016-12-09
Last modified: 2026-06-17

Description

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."

Frequently asked questions

What is 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."
How severe is CVE-2016-8858?: CVE-2016-8858 has a CVSS 3.x base score of 7.5, rated high severity. It is exploitable over network with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is none, integrity none, and availability high.
Is CVE-2016-8858 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 29% (98th percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2016-8858?: CVE-2016-8858 primarily affects Openbsd Openssh. In total, 6 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.
How do I fix CVE-2016-8858?: Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its high severity, prioritise patching exposed systems.
When was CVE-2016-8858 published?: CVE-2016-8858 was published on 2016-12-09 and last updated on 2026-06-17.

References

Affected products (6)

cpe:2.3:a:openbsd:openssh:6.8:*:*:*:*:*:*:*
cpe:2.3:a:openbsd:openssh:6.9:*:*:*:*:*:*:*
cpe:2.3:a:openbsd:openssh:7.0:*:*:*:*:*:*:*
cpe:2.3:a:openbsd:openssh:7.1:*:*:*:*:*:*:*
cpe:2.3:a:openbsd:openssh:7.2:*:*:*:*:*:*:*
cpe:2.3:a:openbsd:openssh:7.3:*:*:*:*:*:*:*

More vulnerabilities in Openbsd Openssh

CVE-2003-0786 — Critical (CVSS 10.0): The SSH1 PAM challenge response authentication in OpenSSH 3.7.1 and 3.7.1p1, when Privilege Separation is disabled,…
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All CVEs affecting Openbsd Openssh →

Other CWE-399 (Resource Management Errors) vulnerabilities

CVE-2015-8104 — Critical (CVSS 10.0): The KVM subsystem in the Linux kernel through 4.2.6, and Xen 4.3.x through 4.6.x, allows guest OS users to cause a…
CVE-2015-0339 — Critical (CVSS 10.0): Adobe Flash Player before 13.0.0.277 and 14.x through 17.x before 17.0.0.134 on Windows and OS X and before…
CVE-2015-0335 — Critical (CVSS 10.0): Adobe Flash Player before 13.0.0.277 and 14.x through 17.x before 17.0.0.134 on Windows and OS X and before…
CVE-2015-0333 — Critical (CVSS 10.0): Adobe Flash Player before 13.0.0.277 and 14.x through 17.x before 17.0.0.134 on Windows and OS X and before…
CVE-2014-4121 — Critical (CVSS 10.0): Microsoft .NET Framework 2.0 SP2, 3.5, 3.5.1, 4, 4.5, 4.5.1, and 4.5.2 does not properly parse internationalized…
CVE-2014-0560 — Critical (CVSS 10.0): Use-after-free vulnerability in Adobe Reader and Acrobat 10.x before 10.1.12 and 11.x before 11.0.09 on Windows and OS…

Browse all CWE-399 (Resource Management Errors) vulnerabilities →

Threat intelligence

Threat-intel indicators referencing this CVE:

183.66.149.42 (ipv4-addr)
111.238.174.6 (ipv4-addr)
41.219.149.74 (ipv4-addr)
223.197.153.143 (ipv4-addr)
67.197.111.225 (ipv4-addr)