CVE-2016-8858
** DISPUTED ** The kex_input_kexinit function in kex.c in OpenSSH 6.x and 7.x through 7.3 allows...
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."
Attack profile
How easy it is to exploit
- Attack vector
- Network
- Complexity
- Low
- Privileges needed
- None
- User interaction
- None
What an attacker can affect
- Confidentiality
- None
- Integrity
- None
- Availability
- High
Exploit likelihood
What each source reports
CVE List
7.5
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."
- Record
CVE-2016-8858- CVSS 3.1
- 7.5 High
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H - Weakness
- CWE-400
- Updated
- 2026-11-02
EUVDEUVD-2016-9683
7.5
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."
- Record
EUVD-2016-9683- CVSS 3.1
- 7.5 High
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H - Updated
- 2026-11-02
GitHub AdvisoriesGHSA-cfx4-r6f2-m2mc
7.5
** DISPUTED ** The kex_input_kexinit function in kex.c in OpenSSH 6.x and 7.x through 7.3 allows...
** DISPUTED ** 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."
- Record
GHSA-cfx4-r6f2-m2mc- CVSS 3.0
- 7.5 High
CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H - Weakness
- CWE-400
- Updated
- 2026-11-02
NVD
7.5
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."
- Record
CVE-2016-8858- CVSS 3.1
- 7.5 High
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H - CVSS 3.0
- 7.5 High
CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H - CVSS 2.0
- 7.8 High
AV:N/AC:L/Au:N/C:N/I:N/A:C - Weakness
- CWE-399, CWE-400
- Updated
- 2026-11-02
OSVBELL-CVE-2016-8858
7.5
CVE-2016-8858 does not affect BellSoft software
- Record
BELL-CVE-2016-8858- CVSS 3.1
- 7.5 High
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H - Updated
- 2026-11-02
OSV
7.5
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."
- Record
CVE-2016-8858- CVSS 3.0
- 7.5 High
CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H - Updated
- 2026-11-02
Show 10 moreShow less
OSVDEBIAN-CVE-2016-8858
7.5
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."
- Record
DEBIAN-CVE-2016-8858- CVSS 3.0
- 7.5 High
CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H - Updated
- 2026-11-02
OSVUBUNTU-CVE-2016-8858
7.5
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."
- Record
UBUNTU-CVE-2016-8858- CVSS 3.1
- 7.5 High
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H - CVSS 3.0
- 7.5 High
CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H - Updated
- 2026-11-02
OSVopenSUSE-SU-2024:11124-1 No score
openssh-8.4p1-7.4 on GA media
These are all security issues fixed in the openssh-8.4p1-7.4 package on the GA media of openSUSE Tumbleweed.
- Record
openSUSE-SU-2024:11124-1- Updated
- 2026-11-02
OSVSUSE-SU-2017:0264-1 No score
Security update for openssh
This update for openssh fixes several issues.
These security issues were fixed:
- CVE-2016-8858: The kex_input_kexinit function in kex.c allowed remote attackers to cause a denial of service (memory consumption) by sending many duplicate KEXINIT requests (bsc#1005480).
- CVE-2016-10012: The shared memory manager (associated with pre-authentication compression) did not ensure that a bounds check is enforced by all compilers, which might allowed local users to gain privileges by leveraging access to a sandboxed privilege-separation process, related to the m_zback and m_zlib data structures (bsc#1016370).
- CVE-2016-10009: Untrusted search path vulnerability in ssh-agent.c allowed remote attackers to execute arbitrary local PKCS#11 modules by leveraging control over a forwarded agent-socket (bsc#1016366).
- CVE-2016-10010: When forwarding unix domain sockets with privilege separation disabled, the resulting sockets have be created as 'root' instead of the authenticated user. Forwarding unix domain sockets without privilege separation enabled is now rejected.
- CVE-2016-10011: authfile.c in sshd did not properly consider the effects of realloc on buffer contents, which might allowed local users to obtain sensitive private-key information by leveraging access to a privilege-separated child process (bsc#1016369).
These non-security issues were fixed:
- Adjusted suggested command for removing conflicting server keys from the known_hosts file (bsc#1006221)
- Properly verify CIDR masks in configuration (bsc#1005893)
- Record
SUSE-SU-2017:0264-1- Updated
- 2026-11-02
OSVSUSE-SU-2017:0603-1 No score
Security update for openssh
This update for openssh fixes the following issues:
Security issues fixed:
- CVE-2016-8858: prevent resource depletion during key exchange (bsc#1005480)
- CVE-2016-10009: limit directories for loading PKCS11 modules to avoid privilege escalation (bsc#1016366)
- CVE-2016-10011: Prevent possible leaks of host private keys to low-privilege process handling authentication (bsc#1016369)
Non security issues fixed:
- Properly verify CIDR masks in the AllowUsers and DenyUsers configuration lists (bsc#1005893)
- fix suggested command for removing conflicting server keys from the known_hosts file (bsc#1006221)
- Record
SUSE-SU-2017:0603-1- Updated
- 2026-11-02
OSVSUSE-SU-2017:0606-1 No score
Security update for openssh
This update for openssh fixes the following issues:
Security issues fixed:
- CVE-2016-8858: prevent resource depletion during key exchange (bsc#1005480)
- CVE-2016-10009: limit directories for loading PKCS11 modules to avoid privilege escalation (bsc#1016366)
- CVE-2016-10011: Prevent possible leaks of host private keys to low-privilege process handling authentication (bsc#1016369)
Non security issues fixed:
- Properly verify CIDR masks in the AllowUsers and DenyUsers configuration lists (bsc#1005893)
- Record
SUSE-SU-2017:0606-1- Updated
- 2026-11-02
OSVSUSE-SU-2017:0607-1 No score
Security update for openssh
This update for openssh fixes the following issues:
-
CVE-2016-8858: prevent resource depletion during key exchange (bsc#1005480)
-
CVE-2016-10009: limit directories for loading PKCS11 modules to avoid privilege escalation (bsc#1016366)
-
CVE-2016-10011: Prevent possible leaks of host private keys to low-privilege process handling authentication (bsc#1016369)
-
Fix suggested command for removing conflicting server keys from the known_hosts file (bsc#1006221)
-
Properly verify CIDR masks in the AllowUsers and DenyUsers configuration lists (bsc#1005893)
- Record
SUSE-SU-2017:0607-1- Updated
- 2026-11-02
OSVSUSE-SU-2017:0607-2 No score
Security update for openssh
This update for openssh fixes the following issues:
-
CVE-2016-8858: prevent resource depletion during key exchange (bsc#1005480)
-
CVE-2016-10009: limit directories for loading PKCS11 modules to avoid privilege escalation (bsc#1016366)
-
CVE-2016-10011: Prevent possible leaks of host private keys to low-privilege process handling authentication (bsc#1016369)
-
Fix suggested command for removing conflicting server keys from the known_hosts file (bsc#1006221)
-
Properly verify CIDR masks in the AllowUsers and DenyUsers configuration lists (bsc#1005893)
- Record
SUSE-SU-2017:0607-2- Updated
- 2026-11-02
OSVSUSE-SU-2017:0607-3 No score
Security update for openssh
This update for openssh fixes the following issues:
-
CVE-2016-8858: prevent resource depletion during key exchange (bsc#1005480)
-
CVE-2016-10009: limit directories for loading PKCS11 modules to avoid privilege escalation (bsc#1016366)
-
CVE-2016-10011: Prevent possible leaks of host private keys to low-privilege process handling authentication (bsc#1016369)
-
Fix suggested command for removing conflicting server keys from the known_hosts file (bsc#1006221)
-
Properly verify CIDR masks in the AllowUsers and DenyUsers configuration lists (bsc#1005893)
- Record
SUSE-SU-2017:0607-3- Updated
- 2026-11-02
OSVSUSE-SU-2017:1661-1 No score
Security update for openssh-openssl1
This update for openssh-openssl1 fixes the following issues:
-
Properly verify CIDR masks in configuration (bsc#1005893)
-
CVE-2016-10009: limit directories for loading PKCS11 modules (bsc#1016366)
-
CVE-2016-10011: Prevent possible leaks of host private keys to low-privilege process handling authentication (bsc#1016369)
-
CVE-2016-8858: prevent resource depletion during key exchange (bsc#1005480)
-
fix suggested command for removing conflicting server keys from the known_hosts file (bsc#1006221)
- Record
SUSE-SU-2017:1661-1- Updated
- 2026-11-02
Affected products
Affected packages
| Package | Affected | Fixed |
|---|---|---|
opensshDebian:12 |
before 1:7.3p1-2 | 1:7.3p1-2 |
opensshDebian:13 |
before 1:7.3p1-2 | 1:7.3p1-2 |
opensshDebian:14 |
before 1:7.3p1-2 | 1:7.3p1-2 |
opensshSUSE:Linux Enterprise Desktop 12 SP2 From an advisory covering 5 CVEs |
before 7.2p2-66.1 | 7.2p2-66.1 |
openssh-askpass-gnomeSUSE:Linux Enterprise Desktop 12 SP2 From an advisory covering 5 CVEs |
before 7.2p2-66.3 | 7.2p2-66.3 |
opensshSUSE:Linux Enterprise Server for Raspberry Pi 12 SP2 From an advisory covering 5 CVEs |
before 7.2p2-66.1 | 7.2p2-66.1 |
openssh-askpass-gnomeSUSE:Linux Enterprise Server for Raspberry Pi 12 SP2 From an advisory covering 5 CVEs |
before 7.2p2-66.3 | 7.2p2-66.3 |
opensshSUSE:Linux Enterprise Server 12 SP2 From an advisory covering 5 CVEs |
before 7.2p2-66.1 | 7.2p2-66.1 |
openssh-askpass-gnomeSUSE:Linux Enterprise Server 12 SP2 From an advisory covering 5 CVEs |
before 7.2p2-66.3 | 7.2p2-66.3 |
opensshSUSE:Linux Enterprise Server for SAP Applications 12 SP2 From an advisory covering 5 CVEs |
before 7.2p2-66.1 | 7.2p2-66.1 |
Show 31 moreShow less
| Package | Affected | Fixed |
|---|---|---|
openssh-askpass-gnomeSUSE:Linux Enterprise Server for SAP Applications 12 SP2 From an advisory covering 5 CVEs |
before 7.2p2-66.3 | 7.2p2-66.3 |
opensshSUSE:Linux Enterprise Server 11 SP4 From an advisory covering 3 CVEs |
before 6.6p1-35.1 | 6.6p1-35.1 |
openssh-askpass-gnomeSUSE:Linux Enterprise Server 11 SP4 From an advisory covering 3 CVEs |
before 6.6p1-35.4 | 6.6p1-35.4 |
opensshSUSE:Linux Enterprise Server for SAP Applications 11 SP4 From an advisory covering 3 CVEs |
before 6.6p1-35.1 | 6.6p1-35.1 |
openssh-askpass-gnomeSUSE:Linux Enterprise Server for SAP Applications 11 SP4 From an advisory covering 3 CVEs |
before 6.6p1-35.4 | 6.6p1-35.4 |
opensshSUSE:OpenStack Cloud 5 From an advisory covering 3 CVEs |
before 6.2p2-0.40.1 | 6.2p2-0.40.1 |
openssh-askpass-gnomeSUSE:OpenStack Cloud 5 From an advisory covering 3 CVEs |
before 6.2p2-0.40.3 | 6.2p2-0.40.3 |
opensshSUSE:Manager 2.1 From an advisory covering 3 CVEs |
before 6.2p2-0.40.1 | 6.2p2-0.40.1 |
openssh-askpass-gnomeSUSE:Manager 2.1 From an advisory covering 3 CVEs |
before 6.2p2-0.40.3 | 6.2p2-0.40.3 |
opensshSUSE:Manager Proxy 2.1 From an advisory covering 3 CVEs |
before 6.2p2-0.40.1 | 6.2p2-0.40.1 |
openssh-askpass-gnomeSUSE:Manager Proxy 2.1 From an advisory covering 3 CVEs |
before 6.2p2-0.40.3 | 6.2p2-0.40.3 |
opensshSUSE:Linux Enterprise Point of Sale 11 SP3 From an advisory covering 3 CVEs |
before 6.2p2-0.40.1 | 6.2p2-0.40.1 |
openssh-askpass-gnomeSUSE:Linux Enterprise Point of Sale 11 SP3 From an advisory covering 3 CVEs |
before 6.2p2-0.40.3 | 6.2p2-0.40.3 |
opensshSUSE:Linux Enterprise Server 11 SP3-LTSS From an advisory covering 3 CVEs |
before 6.2p2-0.40.1 | 6.2p2-0.40.1 |
openssh-askpass-gnomeSUSE:Linux Enterprise Server 11 SP3-LTSS From an advisory covering 3 CVEs |
before 6.2p2-0.40.3 | 6.2p2-0.40.3 |
opensshSUSE:Linux Enterprise Server 11 SP3-TERADATA From an advisory covering 3 CVEs |
before 6.2p2-0.40.1 | 6.2p2-0.40.1 |
openssh-askpass-gnomeSUSE:Linux Enterprise Server 11 SP3-TERADATA From an advisory covering 3 CVEs |
before 6.2p2-0.40.3 | 6.2p2-0.40.3 |
opensshSUSE:Linux Enterprise Server 12 SP1 From an advisory covering 3 CVEs |
before 6.6p1-54.7.1 | 6.6p1-54.7.1 |
openssh-askpass-gnomeSUSE:Linux Enterprise Server 12 SP1 From an advisory covering 3 CVEs |
before 6.6p1-54.7.1 | 6.6p1-54.7.1 |
opensshSUSE:Linux Enterprise Server for SAP Applications 12 SP1 From an advisory covering 3 CVEs |
before 6.6p1-54.7.1 | 6.6p1-54.7.1 |
openssh-askpass-gnomeSUSE:Linux Enterprise Server for SAP Applications 12 SP1 From an advisory covering 3 CVEs |
before 6.6p1-54.7.1 | 6.6p1-54.7.1 |
opensshSUSE:Linux Enterprise Desktop 12 SP1 From an advisory covering 3 CVEs |
before 6.6p1-54.7.1 | 6.6p1-54.7.1 |
openssh-askpass-gnomeSUSE:Linux Enterprise Desktop 12 SP1 From an advisory covering 3 CVEs |
before 6.6p1-54.7.1 | 6.6p1-54.7.1 |
opensshSUSE:Linux Enterprise Server for SAP Applications 12 From an advisory covering 3 CVEs |
before 6.6p1-54.7.1 | 6.6p1-54.7.1 |
openssh-askpass-gnomeSUSE:Linux Enterprise Server for SAP Applications 12 From an advisory covering 3 CVEs |
before 6.6p1-54.7.1 | 6.6p1-54.7.1 |
opensshSUSE:Linux Enterprise Server 12-LTSS From an advisory covering 3 CVEs |
before 6.6p1-54.7.1 | 6.6p1-54.7.1 |
openssh-askpass-gnomeSUSE:Linux Enterprise Server 12-LTSS From an advisory covering 3 CVEs |
before 6.6p1-54.7.1 | 6.6p1-54.7.1 |
openssh-openssl1SUSE:Linux Enterprise Server 11-SECURITY From an advisory covering 3 CVEs |
before 6.6p1-18.1 | 6.6p1-18.1 |
opensshUbuntu:Pro:14.04:LTS |
All versions, plus listed versions 1:6.2p2-61:6.2p2-6ubuntu11:6.4p1-11:6.4p1-21:6.5p1-1 Show 22 moreShow less1:6.5p1-21:6.5p1-31:6.5p1-41:6.5p1-61:6.6p1-11:6.6p1-21:6.6p1-2ubuntu11:6.6p1-2ubuntu21:6.6p1-2ubuntu2.21:6.6p1-2ubuntu2.31:6.6p1-2ubuntu2.41:6.6p1-2ubuntu2.61:6.6p1-2ubuntu2.71:6.6p1-2ubuntu2.81:6.6p1-2ubuntu2.101:6.6p1-2ubuntu2.111:6.6p1-2ubuntu2.121:6.6p1-2ubuntu2.131:6.6p1-2ubuntu2.13+esm11:6.6p1-2ubuntu2.13+esm21:6.6p1-2ubuntu2.13+esm31:6.6p1-2ubuntu2.13+esm4 |
None known |
opensshUbuntu:Pro:16.04:LTS |
All versions, plus listed versions 1:6.9p1-21:6.9p1-31:7.1p1-11:7.1p1-31:7.1p1-4 Show 27 moreShow less1:7.1p1-61:7.1p2-11:7.1p2-21:7.2p1-11:7.2p2-11:7.2p2-21:7.2p2-31:7.2p2-41:7.2p2-4ubuntu11:7.2p2-4ubuntu2.11:7.2p2-4ubuntu2.21:7.2p2-4ubuntu2.41:7.2p2-4ubuntu2.51:7.2p2-4ubuntu2.61:7.2p2-4ubuntu2.71:7.2p2-4ubuntu2.81:7.2p2-4ubuntu2.101:7.2p2-4ubuntu2.10+esm11:7.2p2-4ubuntu2.10+esm21:7.2p2-4ubuntu2.10+esm31:7.2p2-4ubuntu2.10+esm41:7.2p2-4ubuntu2.10+esm51:7.2p2-4ubuntu2.10+esm61:7.2p2-4ubuntu2.10+esm71:7.2p2-4ubuntu2.10+esm81:7.2p2-4ubuntu2.10+esm91:7.2p2-4ubuntu2.10+esm10 |
None known |
opensshopenSUSE:Tumbleweed From an advisory covering 12 CVEs |
before 8.4p1-7.4 | 8.4p1-7.4 |
Public exploits
Links only. Every CVE stores no exploit code.
| Source | Link | Date |
|---|---|---|
| PoC in GitHub | dag-erling/kexkill | 2016-11-03 |
History
| Recorded | Changed | Sources |
|---|---|---|
| affected, facts | ||
| first indexed | CVE List, EUVD, GitHub Advisories, NVD, OSV, PoC in GitHub |
Dates are when Every CVE recorded each change. Upstream dates may differ.
In short
CVE-2016-8858 is a high vulnerability (CVSS 7.5) in Openbsd Openssh, published December 9, 2016. Its validity is disputed. Public exploit code exists. EPSS puts the chance of exploitation in the next 30 days at 29.5%, the 98th percentile. Fixed in openssh 1:7.3p1-2.
References
securityfocus.com/bid/93776
openwall.com/lists/oss-security/2016/10/20/1
security.netapp.com/advisory/ntap-20180201-0001
openwall.com/lists/oss-security/2016/10/19/3
cvsweb.openbsd.org/cgi-bin/cvsweb/src/usr.bin/ssh/kex.c.diff?r1=1.126&r2=1.127&f=h
github.com/openssh/openssh-portable/commit/ec165c392ca54317dbe3064a8c200de6531e89ad
Show 41 moreShow less
ftp.openbsd.org/pub/OpenBSD/patches/6.0/common/013_ssh_kexinit.patch.sig
security.FreeBSD.org/advisories/FreeBSD-SA-16:33.openssh.asc
securitytracker.com/id/1037057
security.gentoo.org/glsa/201612-18
bugzilla.redhat.com/show_bug.cgi?id=1384860
cvsweb.openbsd.org/cgi-bin/cvsweb/src/usr.bin/ssh/kex.c?rev=1.127&content-type=text/x-cvsweb-markup
cert-portal.siemens.com/productcert/pdf/ssa-412672.pdf
nvd.nist.gov/vuln/detail/CVE-2016-8858
github.com/dag-erling/kexkill/issues/1
github.com/advisories/GHSA-cfx4-r6f2-m2mc
docs.bell-sw.com/security/cves/CVE-2016-8858
security-tracker.debian.org/tracker/CVE-2016-8858
suse.com/support/update/announcement/2017/suse-su-20170264-1
bugzilla.suse.com/1005480
bugzilla.suse.com/1005893
bugzilla.suse.com/1006221
bugzilla.suse.com/1016366
bugzilla.suse.com/1016368
bugzilla.suse.com/1016369
bugzilla.suse.com/1016370
suse.com/security/cve/CVE-2016-10009
suse.com/security/cve/CVE-2016-10010
suse.com/security/cve/CVE-2016-10011
suse.com/security/cve/CVE-2016-10012
suse.com/security/cve/CVE-2016-8858
suse.com/support/update/announcement/2017/suse-su-20170603-1
suse.com/support/update/announcement/2017/suse-su-20170606-1
suse.com/support/update/announcement/2017/suse-su-20170607-1
suse.com/support/update/announcement/2017/suse-su-20170607-2
suse.com/support/update/announcement/2017/suse-su-20170607-3
suse.com/support/update/announcement/2017/suse-su-20171661-1
ubuntu.com/security/CVE-2016-8858
seclists.org/oss-sec/2016/q4/185
cve.org/CVERecord?id=CVE-2016-8858
suse.com/security/cve/CVE-2006-0225
suse.com/security/cve/CVE-2007-4752
suse.com/security/cve/CVE-2008-1483
suse.com/security/cve/CVE-2018-20685
suse.com/security/cve/CVE-2019-6109
suse.com/security/cve/CVE-2019-6110
suse.com/security/cve/CVE-2019-6111