CVE-2016-9603

A heap buffer overflow flaw was found in QEMU's Cirrus CLGD 54xx VGA emulator's VNC display driver support before 2.9; the issue could occur when a VNC client attempted to update its display after a VGA operation is performed by a guest. A privileged user/process inside a guest could use this flaw to crash the QEMU process or, potentially, execute arbitrary code on the host with privileges of the QEMU process.

Published: 2018-07-27 Last update: 2024-11-21 Assigner: [email protected] Source: [email protected]
NVD Status：Modified，CVE State: published
View at NVD, CVE.org, EUVD

CVE-2016-9603 is rated Moderate Risk (45.3/100): CVSS Medium severity, with medium exploitation likelihood (EPSS 0.59%). Review affected assets and schedule 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-2016-9603

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 2026-05-17 1.59% 0.59% -1.00%
2 2026-02-10 1.38% 1.59% +0.21%
3 2025-12-14 — 1.38% —

Full EPSS history (14 records total)

Common vulnerability scoring system (CVSS) metrics for CVE-2016-9603

CVSS metrics for this CVE.

Base score Version Severity Vector Exploitability Impact Score source
5.5 3.0 MEDIUM
CVSS:3.0/AV:A/AC:H/PR:L/UI:N/S:C/C:L/I:L/A:L Click to expand
Attack vector (AV:A)
Attacker has to be nearby on the network—same office, same link, that vibe—not the whole wide internet.
Attack complexity (AC:H)
Even with access, the exploit needs extra luck, timing, or a fussy environment to actually work.
Privileges required (PR:L)
A normal user session is enough; they don’t have to be admin.
User interaction (UI:N)
Nobody has to click “OK” or open a trap file; it can work without a victim helping.
Scope (S:C)
Breaking this can reach past the original component and bite other resources—bigger blast radius.
Confidentiality (C:L)
Some sensitive info could get out, but not a total data dump.
Integrity (I:L)
Attackers could change some data, but it’s limited—not everything goes.
Availability (A:L)
Might cause slowdowns, glitches, or partial disruption—not a full brick.
 1.3 3.7 [email protected]
9.9 3.0 CRITICAL
CVSS:3.0/AV:N/AC:L/PR:L/UI:N/S:C/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:L)
A normal user session is enough; they don’t have to be admin.
User interaction (UI:N)
Nobody has to click “OK” or open a trap file; it can work without a victim helping.
Scope (S:C)
Breaking this can reach past the original component and bite other resources—bigger blast radius.
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.
 3.1 6.0 [email protected]
9.0 2.0 HIGH
AV:N/AC:L/Au:S/C:C/I:C/A:C 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:S)
A single authentication is required.
Confidentiality impact (C:C)
Complete confidentiality impact.
Integrity impact (I:C)
Complete integrity impact.
Availability impact (A:C)
Complete availability impact.
 8.0 10.0 [email protected]

Weakness enumeration for CVE-2016-9603

OS Trackers for CVE-2016-9603

vendor priority summary link
alpine — CVE-2016-9603: 1 source package rows (xen); 10 state rows across 10 repos (3.10-main, 3.11-main, 3.12-main, 3.17-main, 3.18-main, 3.19-main, 3.20-main, 3.21-main, 3.22-main, edge-main); fixed 10, open 0. https://security.alpinelinux.org/vuln/CVE-2016-9603
debian not yet assigned CVE-2016-9603 not yet assigned priority: Debian including 2 source packages (qemu, xen), 10 status rows across 5 suites (bookworm, bullseye, forky, sid, trixie): resolved 10. https://security-tracker.debian.org/tracker/CVE-2016-9603
gentoo normal CVE-2016-9603: 1 GLSA(s) (201706-03), 1 atom(s) (app-emulation/qemu); latest impact normal. https://bugs.gentoo.org/buglist.cgi?quicksearch=CVE-2016-9603
redhat high — https://access.redhat.com/security/cve/CVE-2016-9603
suse low CVE-2016-9603 severity low: SUSE including 112 source package names (kvm-1.4.2-53.11.1, kvm-1.4.2-60.3.1, …), 276 product×package rows across 33 product lines (SUSE Liberty Linux 7, SUSE Linux Enterprise Desktop 12 SP1, … (33 product lines)): Fixed 230, Known Not Affected 46. https://www.suse.com/security/cve/CVE-2016-9603/
ubuntu medium CVE-2016-9603 medium priority: Ubuntu including 3 source packages (qemu, qemu-kvm, xen), 18 status rows across 6 suites (precise, trusty, upstream, xenial, yakkety, zesty): DNE 5, released 5, not-affected 4, needs-triage 2, ignored 1, needed 1. https://ubuntu.com/security/CVE-2016-9603

Affected software / configurations for CVE-2016-9603

Vendor Product Version Raw CPE
qemu qemu < 2.9.0 cpe:2.3:a:qemu:qemu:*:*:*:*:*:*:*:*
citrix xenserver 6.0.2 cpe:2.3:a:citrix:xenserver:6.0.2:*:*:*:*:*:*:*
citrix xenserver 6.2.0 cpe:2.3:a:citrix:xenserver:6.2.0:sp1:*:*:*:*:*:*
citrix xenserver 6.5 cpe:2.3:a:citrix:xenserver:6.5:sp1:*:*:*:*:*:*
citrix xenserver 7.0 cpe:2.3:a:citrix:xenserver:7.0:*:*:*:*:*:*:*
citrix xenserver 7.1 cpe:2.3:a:citrix:xenserver:7.1:*:*:*:*:*:*:*
redhat openstack 5.0 cpe:2.3:a:redhat:openstack:5.0:*:*:*:*:*:*:*
redhat openstack 6.0 cpe:2.3:a:redhat:openstack:6.0:*:*:*:*:*:*:*
redhat openstack 7.0 cpe:2.3:a:redhat:openstack:7.0:*:*:*:*:*:*:*
redhat openstack 8 cpe:2.3:a:redhat:openstack:8:*:*:*:*:*:*:*
redhat openstack 9 cpe:2.3:a:redhat:openstack:9:*:*:*:*:*:*:*
redhat openstack 10 cpe:2.3:a:redhat:openstack:10:*:*:*:*:*:*:*
debian debian_linux 7.0 cpe:2.3:o:debian:debian_linux:7.0:*:*:*:*:*:*:*
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_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 7.3 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_eus 7.3 cpe:2.3:o:redhat:enterprise_linux_server_eus:7.3:*:*:*:*:*:*:*
redhat enterprise_linux_server_eus 7.4 cpe:2.3:o:redhat:enterprise_linux_server_eus:7.4:*:*:*:*:*:*:*
redhat enterprise_linux_server_eus 7.5 cpe:2.3:o:redhat:enterprise_linux_server_eus:7.5:*:*:*:*:*:*:*
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-2016-9603

URL Tags
http://www.securityfocus.com/bid/96893 Third Party Advisory VDB Entry
http://www.securitytracker.com/id/1038023 Third Party Advisory VDB Entry
https://access.redhat.com/errata/RHSA-2017:0980 Third Party Advisory
https://access.redhat.com/errata/RHSA-2017:0981 Third Party Advisory
https://access.redhat.com/errata/RHSA-2017:0982 Third Party Advisory
https://access.redhat.com/errata/RHSA-2017:0983 Third Party Advisory
https://access.redhat.com/errata/RHSA-2017:0984 Third Party Advisory
https://access.redhat.com/errata/RHSA-2017:0985 Third Party Advisory
https://access.redhat.com/errata/RHSA-2017:0987 Third Party Advisory
https://access.redhat.com/errata/RHSA-2017:0988 Third Party Advisory
https://access.redhat.com/errata/RHSA-2017:1205 Third Party Advisory
https://access.redhat.com/errata/RHSA-2017:1206 Third Party Advisory
https://access.redhat.com/errata/RHSA-2017:1441 Third Party Advisory
https://bugzilla.redhat.com/show_bug.cgi?id=CVE-2016-9603 Issue Tracking Third Party Advisory
https://lists.debian.org/debian-lts-announce/2018/02/msg00005.html Third Party Advisory
https://lists.debian.org/debian-lts-announce/2018/09/msg00007.html
https://security.gentoo.org/glsa/201706-03 Third Party Advisory
https://support.citrix.com/article/CTX221578 Third Party Advisory
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