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CVE-2016-8858

7.5 · HIGH

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.

Published Dec 9, 2016CWE-399EPSS 29.46%

Overview

CVE-2016-8858 is a high-severity vulnerability. It was published on December 9, 2016 and has a CVSS 3.1 base score of 7.5 (HIGH).

This vulnerability has a CVSS 3.1 base score of 7.5, rated HIGH. It can be exploited remotely over the network. No authentication or special privileges are required for exploitation.

Technical 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."

Remediation

Check the references section for vendor advisories, patches, and mitigation guidance. If immediate patching is not possible, review the CVSS vector to understand the attack surface and apply compensating controls such as network segmentation or access restrictions.

References

Refcvsweb.openbsd.org/cgi-bin/cvsweb/src/usr.bin/ssh/kex.c.diff?r1=1.126&r2=1.127&f=hRefcvsweb.openbsd.org/cgi-bin/cvsweb/src/usr.bin/ssh/kex.c?rev=1.127&content-type=text/x-cvsweb-markupRefwww.openwall.com/lists/oss-security/2016/10/19/3Refwww.openwall.com/lists/oss-security/2016/10/20/1Refwww.securityfocus.com/bid/93776Refwww.securitytracker.com/id/1037057Refbugzilla.redhat.com/show_bug.cgi?id=1384860Refcert-portal.siemens.com/productcert/pdf/ssa-412672.pdfRefftp.openbsd.org/pub/OpenBSD/patches/6.0/common/013_ssh_kexinit.patch.sigGitHubgithub.com/openssh/openssh-portable/commit/ec165c392ca54317dbe3064a8c200de6531e89ad

How CyberStrike helps

Frequently asked questions

What is CVE-2016-8858?

CVE-2016-8858 is a high-severity vulnerability. It was published on December 9, 2016 and has a CVSS 3.1 base score of 7.5 (HIGH).

How severe is CVE-2016-8858?

This vulnerability has a CVSS 3.1 base score of 7.5, rated HIGH. It can be exploited remotely over the network. No authentication or special privileges are required for exploitation.

How do I fix or remediate CVE-2016-8858?

Check the references section for vendor advisories, patches, and mitigation guidance. If immediate patching is not possible, review the CVSS vector to understand the attack surface and apply compensating controls such as network segmentation or access restrictions.

How can CyberStrike help with CVE-2016-8858?

CyberStrike is an open-source, AI-augmented pentesting engine. Rather than flag a version number, it tests whether an issue like CVE-2016-8858 is actually reachable in your own applications and APIs, then verifies each finding before reporting it. That tells you if the weakness is a real, exploitable risk in your environment or a false positive you can safely deprioritize.

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