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."
Fixed in Linux distributions
Distributions backport fixes, so the version that fixes this vulnerability differs per release — upgrade to at least the version shown. From the distributions' security trackers and advisories.
Debian
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Debian 14 | openssh | 1:7.3p1-2 | — |
| Debian 13 | openssh | 1:7.3p1-2 | — |
| Debian 12 | openssh | 1:7.3p1-2 | — |
Ubuntu
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Ubuntu Pro 16.04 LTS | openssh | No fix yet | — |
| Ubuntu Pro 14.04 LTS | openssh | No fix yet | — |
SUSE
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| SLES 12 SP2 | openssh | 7.2p2-66.1 | SUSE-SU-2017:0264-1 |
| SLES 12 SP2 | openssh-askpass-gnome | 7.2p2-66.3 | SUSE-SU-2017:0264-1 |
| SLES 12 SP1 | openssh +1 | 6.6p1-54.7.1 | SUSE-SU-2017:0607-2, SUSE-SU-2017:0607-1 |
| SLES 12 | openssh +1 | 6.6p1-54.7.1 | SUSE-SU-2017:0607-3 |
| SLES 11 SP4 | openssh | 6.6p1-35.1 | SUSE-SU-2017:0603-1 |
| SLES 11 SP4 | openssh-askpass-gnome | 6.6p1-35.4 | SUSE-SU-2017:0603-1 |
| SLES 11 SP3 | openssh | 6.2p2-0.40.1 | SUSE-SU-2017:0606-1 |
| SLES 11 SP3 | openssh-askpass-gnome | 6.2p2-0.40.3 | SUSE-SU-2017:0606-1 |
Show 9 more (older releases, extended support, other products)Fewer releases
| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| SLES 11 | openssh-openssl1 | 6.6p1-18.1 | SUSE-SU-2017:1661-1 |
| SLES for SAP 12 SP2 | openssh | 7.2p2-66.1 | SUSE-SU-2017:0264-1 |
| SLES for SAP 12 SP2 | openssh-askpass-gnome | 7.2p2-66.3 | SUSE-SU-2017:0264-1 |
| SLES for SAP 12 SP1 | openssh +1 | 6.6p1-54.7.1 | SUSE-SU-2017:0607-2, SUSE-SU-2017:0607-1 |
| SLES for SAP 12 | openssh +1 | 6.6p1-54.7.1 | SUSE-SU-2017:0607-2 |
| SLES for SAP 11 SP4 | openssh | 6.6p1-35.1 | SUSE-SU-2017:0603-1 |
| SLES for SAP 11 SP4 | openssh-askpass-gnome | 6.6p1-35.4 | SUSE-SU-2017:0603-1 |
| SUSE OpenStack Cloud 5 | openssh | 6.2p2-0.40.1 | SUSE-SU-2017:0606-1 |
| SUSE OpenStack Cloud 5 | openssh-askpass-gnome | 6.2p2-0.40.3 | SUSE-SU-2017:0606-1 |
| SUSE Manager Proxy 2.1 | openssh | 6.2p2-0.40.1 | SUSE-SU-2017:0606-1 |
| SUSE Manager Proxy 2.1 | openssh-askpass-gnome | 6.2p2-0.40.3 | SUSE-SU-2017:0606-1 |
| SUSE Manager 2.1 | openssh | 6.2p2-0.40.1 | SUSE-SU-2017:0606-1 |
| SUSE Manager 2.1 | openssh-askpass-gnome | 6.2p2-0.40.3 | SUSE-SU-2017:0606-1 |
| SUSE Linux Enterprise Point of Sale 11 SP3 | openssh | 6.2p2-0.40.1 | SUSE-SU-2017:0606-1 |
| SUSE Linux Enterprise Point of Sale 11 SP3 | openssh-askpass-gnome | 6.2p2-0.40.3 | SUSE-SU-2017:0606-1 |
openSUSE
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| openSUSE Tumbleweed | openssh | 8.4p1-7.4 | openSUSE-SU-2024:11124-1 |
Public exploits
Exploit or proof-of-concept code for this vulnerability is publicly available, which lowers the bar for attackers. Treat it as a reason to patch sooner.
Third-party code, not reviewed by us. Public PoCs are sometimes fake or contain malware. Read the code first and run it only in an isolated lab, against systems you are authorised to test.
GitHub 1 repository
-
dag-erling/kexkill ★ 7 · Nov 3, 2016
Proof of concept for CVE-2016-8858
Sources: PoC-in-GitHub, Metasploit Framework, Exploit-DB — updated daily. Only links are listed; no exploit code is hosted here.
Advisories 11
- SUSE-SU-2017:0603-1 Security update for openssh SUSE / openSUSE Security Updates · Feb 4, 2026
- SUSE-SU-2017:0264-1 Security update for openssh SUSE / openSUSE Security Updates · Feb 4, 2026
- openSUSE-SU-2024:11124-1 openssh-8.4p1-7.4 on GA media SUSE / openSUSE Security Updates · Feb 4, 2026
- SUSE-SU-2017:0606-1 Security update for openssh SUSE / openSUSE Security Updates · Feb 4, 2026
- SUSE-SU-2017:0607-3 Security update for openssh SUSE / openSUSE Security Updates · Feb 4, 2026
- SUSE-SU-2017:0607-2 Security update for openssh SUSE / openSUSE Security Updates · Feb 4, 2026
- SUSE-SU-2017:0607-1 Security update for openssh SUSE / openSUSE Security Updates · Feb 4, 2026
- SUSE-SU-2017:1661-1 Security update for openssh-openssl1 SUSE / openSUSE Security Updates · May 2, 2025
- WID-SEC-2024-1052 OpenSSH: Schwachstelle ermöglicht Denial of Service BSI CERT-Bund (WID) · May 7, 2024
- ICSA-22-349-21 Siemens SCALANCE X-200RNA Switch Devices CISA ICS & IT advisories · Dec 13, 2022
- SSA-412672 SSA-412672: Multiple OpenSSL and OpenSSH Vulnerabilities in SCALANCE X-200RNA Switch Devices before V3.2.7 Siemens ProductCERT · Dec 13, 2022
References
- 93776 vdb-entry
- [oss-security] 20161020 Re: Re: CVE Request: OpenSSH: Memory exhaustion issue found in OpenSSH mailing-list
- https://security.netapp.com/advisory/ntap-20180201-0001/
- [oss-security] 20161019 CVE Request: OpenSSH: Memory exhaustion issue found in OpenSSH mailing-list
- http://cvsweb.openbsd.org/cgi-bin/cvsweb/src/usr.bin/ssh/kex.c.diff?r1=1.126&r2=1.127&f=h
- https://github.com/openssh/openssh-portable/commit/ec165c392ca54317dbe3064a8c200de6531e89ad
- https://ftp.openbsd.org/pub/OpenBSD/patches/6.0/common/013_ssh_kexinit.patch.sig
- FreeBSD-SA-16:33 vendor-advisory
- 1037057 vdb-entry
- GLSA-201612-18 vendor-advisory
- https://bugzilla.redhat.com/show_bug.cgi?id=1384860
- http://cvsweb.openbsd.org/cgi-bin/cvsweb/src/usr.bin/ssh/kex.c?rev=1.127&content-type=text/x-cvsweb-markup
- https://cert-portal.siemens.com/productcert/pdf/ssa-412672.pdf