CVE-2016-8858
HIGHCVSS 7.5/10EPSS 29.46%
Last modified
CVE-2016-8858 is a high-severity vulnerability rated 7.5/10 on the CVSS scale. 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.". EPSS estimates a 29.46% chance of exploitation in the next 30 days.
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."
Metrics
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
Weakness Enumeration
Affected Software
| Vendor | Product | Versions |
|---|---|---|
| Openbsd | Openssh | 6.8 |
| Openbsd | Openssh | 6.9 |
| Openbsd | Openssh | 7.0 |
| Openbsd | Openssh | 7.1 |
| Openbsd | Openssh | 7.2 |
| Openbsd | Openssh | 7.3 |
References
- http://cvsweb.openbsd.org/cgi-bin/cvsweb/src/usr.bin/ssh/kex.c.diff?r1=1.126&r2=1.127&f=hIssue Tracking, Vendor Advisory
- http://cvsweb.openbsd.org/cgi-bin/cvsweb/src/usr.bin/ssh/kex.c?rev=1.127&content-type=text/x-cvsweb-markupIssue Tracking, Vendor Advisory
- http://www.openwall.com/lists/oss-security/2016/10/19/3Mailing List, Third Party Advisory
- http://www.openwall.com/lists/oss-security/2016/10/20/1Mailing List, Third Party Advisory
- http://www.securityfocus.com/bid/93776Third Party Advisory, VDB Entry
- http://www.securitytracker.com/id/1037057Third Party Advisory, VDB Entry
- https://bugzilla.redhat.com/show_bug.cgi?id=1384860Issue Tracking
- https://ftp.openbsd.org/pub/OpenBSD/patches/6.0/common/013_ssh_kexinit.patch.sigPatch, Vendor Advisory
- https://github.com/openssh/openssh-portable/commit/ec165c392ca54317dbe3064a8c200de6531e89adIssue Tracking, Patch, Third Party Advisory
- https://security.FreeBSD.org/advisories/FreeBSD-SA-16:33.openssh.ascThird Party Advisory
- https://security.gentoo.org/glsa/201612-18Third Party Advisory
- https://security.netapp.com/advisory/ntap-20180201-0001/Third Party Advisory
- http://cvsweb.openbsd.org/cgi-bin/cvsweb/src/usr.bin/ssh/kex.c.diff?r1=1.126&r2=1.127&f=hIssue Tracking, Vendor Advisory
- http://cvsweb.openbsd.org/cgi-bin/cvsweb/src/usr.bin/ssh/kex.c?rev=1.127&content-type=text/x-cvsweb-markupIssue Tracking, Vendor Advisory
- http://www.openwall.com/lists/oss-security/2016/10/19/3Mailing List, Third Party Advisory
- http://www.openwall.com/lists/oss-security/2016/10/20/1Mailing List, Third Party Advisory
- http://www.securityfocus.com/bid/93776Third Party Advisory, VDB Entry
- http://www.securitytracker.com/id/1037057Third Party Advisory, VDB Entry
- https://bugzilla.redhat.com/show_bug.cgi?id=1384860Issue Tracking
- https://ftp.openbsd.org/pub/OpenBSD/patches/6.0/common/013_ssh_kexinit.patch.sigPatch, Vendor Advisory
- https://github.com/openssh/openssh-portable/commit/ec165c392ca54317dbe3064a8c200de6531e89adIssue Tracking, Patch, Third Party Advisory
- https://security.FreeBSD.org/advisories/FreeBSD-SA-16:33.openssh.ascThird Party Advisory
- https://security.gentoo.org/glsa/201612-18Third Party Advisory
- https://security.netapp.com/advisory/ntap-20180201-0001/Third Party Advisory
Timeline
- Published
- Last Modified
- Status
- Modified
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 score of 7.5/10 (HIGH severity). The EPSS model estimates a 29.46% probability of exploitation in the next 30 days.
How do I fix CVE-2016-8858?
Check the vendor references and advisories linked above for patched versions and mitigation guidance. You can also run a Strix scan to test if your systems are affected.
How Strix Helps
- How Strix found a critical auth bypass in etcdStrix autonomously discovered a critical authentication bypass in etcd, later designated CVE-2026-33413.
- Autonomous PentestingAI agents that find and validate exploitable vulnerabilities like this one across your applications.
- PR ReviewsPentest every pull request so vulnerable code is caught before it ships to production.
- AI Penetration TestingHow AI-driven penetration testing continuously covers your attack surface.
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- CVE-2016-8854Rejected reason: DO NOT USE THIS CANDIDATE NUMBER. ConsultI…
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