CVE-2016-1908

The client in OpenSSH before 7.2 mishandles failed cookie generation for untrusted X11 forwarding and relies on the local X11 server for access-control decisions, which allows remote X11 clients to trigger a fallback and obtain trusted X11 forwarding privileges by leveraging configuration issues on this X11 server, as demonstrated by lack of the SECURITY extension on this X11 server.

Published: 2017-04-11 Last update: 2026-05-29 Assigner: [email protected] Source: [email protected]
NVD Status：Modified，CVE State: published
View at NVD, CVE.org, EUVD

CVE-2016-1908 is rated High Risk (77.8/100): CVSS Critical severity, with high exploitation likelihood (EPSS 13.74%, 96th percentile). EPSS ranks this CVE among the most likely to be exploited in the near term. EPSS rose +11.37% over the last day, indicating growing attacker interest. High exploitation likelihood—assess exposure and prioritize remediation.

Risk is dynamic; we continuously reassess and refresh what is shown on this page as upstream context changes.

Exploit prediction scoring system (EPSS) score for CVE-2016-1908

EPSS lead: Daily EPSS estimates relative likelihood of exploitation; percentile ranks this CVE among scored vulnerabilities (higher = more severe relative rank).

# Date Old EPSS score New EPSS score Delta (New - Old)
1 2026-06-15 2.37% 13.74% +11.37%
2 2026-05-11 2.18% 2.37% +0.19%
3 2026-03-19 — 2.18% —

Full EPSS history (54 records total)

Common vulnerability scoring system (CVSS) metrics for CVE-2016-1908

CVSS metrics for this CVE.

Base score Version Severity Vector Exploitability Impact Score source
9.8 3.1 CRITICAL
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H Click to expand
Attack vector (AV:N)
Could be attacked over the internet or any normal routed network—not just someone sitting at the machine.
Attack complexity (AC:L)
Once they can reach the bug, pulling it off is straightforward—no weird race conditions or rare setup.
Privileges required (PR:N)
No account or special rights needed—anonymous or random user is enough.
User interaction (UI:N)
Nobody has to click “OK” or open a trap file; it can work without a victim helping.
Scope (S:U)
Damage stays in the same “trust bubble” as the broken component—no big spill into unrelated systems.
Confidentiality (C:H)
Serious risk that confidential data gets exposed in a big way.
Integrity (I:H)
They could widely tamper with or forge data—trust in the data is badly hurt.
Availability (A:H)
Could take the service down hard or make it unusable for people who depend on it.
 3.9 5.9 [email protected]
9.8 3.1 CRITICAL
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H Click to expand
Attack vector (AV:N)
Could be attacked over the internet or any normal routed network—not just someone sitting at the machine.
Attack complexity (AC:L)
Once they can reach the bug, pulling it off is straightforward—no weird race conditions or rare setup.
Privileges required (PR:N)
No account or special rights needed—anonymous or random user is enough.
User interaction (UI:N)
Nobody has to click “OK” or open a trap file; it can work without a victim helping.
Scope (S:U)
Damage stays in the same “trust bubble” as the broken component—no big spill into unrelated systems.
Confidentiality (C:H)
Serious risk that confidential data gets exposed in a big way.
Integrity (I:H)
They could widely tamper with or forge data—trust in the data is badly hurt.
Availability (A:H)
Could take the service down hard or make it unusable for people who depend on it.
 3.9 5.9 134c704f-9b21-4f2e-91b3-4a467353bcc0
7.5 2.0 HIGH
AV:N/AC:L/Au:N/C:P/I:P/A:P Click to expand
Access vector (AV:N)
Can be exploited remotely over network reachability.
Access complexity (AC:L)
Exploitation conditions are straightforward and predictable.
Authentication (AU:N)
No authentication is required.
Confidentiality impact (C:P)
Partial confidentiality impact.
Integrity impact (I:P)
Partial integrity impact.
Availability impact (A:P)
Partial availability impact.
 10.0 6.4 [email protected]

Weakness enumeration for CVE-2016-1908

OS Trackers for CVE-2016-1908

vendor priority summary link
debian not yet assigned CVE-2016-1908 not yet assigned priority: Debian including 1 source packages (openssh), 5 status rows across 5 suites (bookworm, bullseye, forky, sid, trixie): resolved 5. https://security-tracker.debian.org/tracker/CVE-2016-1908
gentoo normal CVE-2016-1908: 1 GLSA(s) (201612-18), 1 atom(s) (net-misc/openssh); latest impact normal. https://bugs.gentoo.org/buglist.cgi?quicksearch=CVE-2016-1908
redhat medium — https://access.redhat.com/security/cve/CVE-2016-1908
suse low CVE-2016-1908 severity low: SUSE including 36 source package names (openssh-5.1p1-41.74.1, openssh-6.2p2-0.33.2, …), 90 product×package rows across 27 product lines (SUSE Liberty Linux 7, SUSE Linux Enterprise Desktop 12, … (27 product lines)): Fixed 90. https://www.suse.com/security/cve/CVE-2016-1908/
ubuntu low CVE-2016-1908 low priority: Ubuntu including 1 source packages (openssh), 8 status rows across 8 suites (precise, trusty, upstream, vivid, wily, xenial, yakkety, zesty): released 4, not-affected 3, ignored 1. https://ubuntu.com/security/CVE-2016-1908

Affected software / configurations for CVE-2016-1908

Vendor Product Version Raw CPE
openbsd openssh < 7.2 cpe:2.3:a:openbsd:openssh:*:*:*:*:*:*:*:*
debian debian_linux 8.0 cpe:2.3:o:debian:debian_linux:8.0:*:*:*:*:*:*:*
oracle linux 6 cpe:2.3:o:oracle:linux:6:-:*:*:*:*:*:*
oracle linux 7 cpe:2.3:o:oracle:linux:7:-:*:*:*:*:*:*
redhat enterprise_linux_desktop 6.0 cpe:2.3:o:redhat:enterprise_linux_desktop:6.0:*:*:*:*:*:*:*
redhat enterprise_linux_desktop 7.0 cpe:2.3:o:redhat:enterprise_linux_desktop:7.0:*:*:*:*:*:*:*
redhat enterprise_linux_eus 7.2 cpe:2.3:o:redhat:enterprise_linux_eus:7.2:*:*:*:*:*:*:*
redhat enterprise_linux_eus 7.3 cpe:2.3:o:redhat:enterprise_linux_eus:7.3:*:*:*:*:*:*:*
redhat enterprise_linux_eus 7.4 cpe:2.3:o:redhat:enterprise_linux_eus:7.4:*:*:*:*:*:*:*
redhat enterprise_linux_eus 7.5 cpe:2.3:o:redhat:enterprise_linux_eus:7.5:*:*:*:*:*:*:*
redhat enterprise_linux_eus 7.6 cpe:2.3:o:redhat:enterprise_linux_eus:7.6:*:*:*:*:*:*:*
redhat enterprise_linux_eus 7.7 cpe:2.3:o:redhat:enterprise_linux_eus:7.7:*:*:*:*:*:*:*
redhat enterprise_linux_server 6.0 cpe:2.3:o:redhat:enterprise_linux_server:6.0:*:*:*:*:*:*:*
redhat enterprise_linux_server 7.0 cpe:2.3:o:redhat:enterprise_linux_server:7.0:*:*:*:*:*:*:*
redhat enterprise_linux_server_aus 7.2 cpe:2.3:o:redhat:enterprise_linux_server_aus:7.2:*:*:*:*:*:*:*
redhat enterprise_linux_server_aus 7.3 cpe:2.3:o:redhat:enterprise_linux_server_aus:7.3:*:*:*:*:*:*:*
redhat enterprise_linux_server_aus 7.4 cpe:2.3:o:redhat:enterprise_linux_server_aus:7.4:*:*:*:*:*:*:*
redhat enterprise_linux_server_aus 7.6 cpe:2.3:o:redhat:enterprise_linux_server_aus:7.6:*:*:*:*:*:*:*
redhat enterprise_linux_server_aus 7.7 cpe:2.3:o:redhat:enterprise_linux_server_aus:7.7:*:*:*:*:*:*:*
redhat enterprise_linux_server_tus 7.2 cpe:2.3:o:redhat:enterprise_linux_server_tus:7.2:*:*:*:*:*:*:*
redhat enterprise_linux_server_tus 7.3 cpe:2.3:o:redhat:enterprise_linux_server_tus:7.3:*:*:*:*:*:*:*
redhat enterprise_linux_server_tus 7.6 cpe:2.3:o:redhat:enterprise_linux_server_tus:7.6:*:*:*:*:*:*:*
redhat enterprise_linux_server_tus 7.7 cpe:2.3:o:redhat:enterprise_linux_server_tus:7.7:*:*:*:*:*:*:*
redhat enterprise_linux_workstation 6.0 cpe:2.3:o:redhat:enterprise_linux_workstation:6.0:*:*:*:*:*:*:*
redhat enterprise_linux_workstation 7.0 cpe:2.3:o:redhat:enterprise_linux_workstation:7.0:*:*:*:*:*:*:*

References for CVE-2016-1908

URL Tags
http://openwall.com/lists/oss-security/2016/01/15/13 Mailing List Third Party Advisory
http://rhn.redhat.com/errata/RHSA-2016-0465.html Third Party Advisory
http://rhn.redhat.com/errata/RHSA-2016-0741.html Third Party Advisory
http://www.openssh.com/txt/release-7.2 Release Notes Vendor Advisory
http://www.oracle.com/technetwork/topics/security/linuxbulletinapr2016-2952096.html Third Party Advisory
http://www.securityfocus.com/bid/84427 Third Party Advisory VDB Entry
http://www.securitytracker.com/id/1034705 Broken Link Third Party Advisory VDB Entry
https://anongit.mindrot.org/openssh.git/commit/?id=ed4ce82dbfa8a3a3c8ea6fa0db113c71e234416c Patch Third Party Advisory
https://bugzilla.redhat.com/show_bug.cgi?id=1298741 Issue Tracking Patch Third Party Advisory
https://cert-portal.siemens.com/productcert/pdf/ssa-412672.pdf
https://lists.debian.org/debian-lts-announce/2018/09/msg00010.html Mailing List Third Party Advisory
https://security.gentoo.org/glsa/201612-18 Third Party Advisory
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