What is CVE-2016-4439?

CVE-2016-4439 is a medium-severity vulnerability in Qemu, classified under Improper Restriction of Operations within the Bounds of a Memory Buffer. CVSS score: 6.7/10. Published 2016-05-20.

How severe is CVE-2016-4439?

Medium severity. CVSS v3 base score is 6.7 out of 10.

Buffer overflow in Qemu

CVE-2016-4439

The esp_reg_write function in hw/scsi/esp.c in the 53C9X Fast SCSI Controller (FSC) support in QEMU does not properly check command buffer length, which allows local guest OS administrators to cause a denial of service (out-of-bounds write and QEMU process crash) or potentially execute arbitrary code on the QEMU host via unspecified vectors.

Vulnerability class: Buffer Overflow

Published 2016-05-20 · last modified 2026-06-17.

CVSS v3 metric

CVSS v3 base score 6.7 (Medium). Vector: CVSS:3.1/AV:L/AC:L/PR:H/UI:N/S:U/C:H/I:H/A:H.

EPSS exploit prediction

EPSS: 0.005 (37.5th percentile), scored 2026-10-02.

Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 37th percentile — 37.5% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.

EPSS over last 30 days · oldest: 0.005 · newest: 0.005 · change: 0.000

Affected products

Qemu
Canonical Ubuntu Linux — versions 12.04, 14.04, 16.04
Debian Linux — versions 8.0

Weakness classification (CWE)

CWE-119 — Improper Restriction of Operations within the Bounds of a Memory Buffer

References

www.ubuntu.com/usn/USN-3047-1 (vendor-advisory, Third Party Advisory)
www.securityfocus.com/bid/90760 (VDB Entry, Third Party Advisory, vdb-entry)
security.gentoo.org/glsa/201609-01 (vendor-advisory, Third Party Advisory)
www.ubuntu.com/usn/USN-3047-2 (vendor-advisory, Third Party Advisory)
lists.gnu.org/archive/html/qemu-devel/2016-05/msg03273.html (mailing-list, Patch, Mailing List, Third Party Advisory)
www.openwall.com/lists/oss-security/2016/05/19/3 (mailing-list, Patch, Mailing List, Third Party Advisory)
lists.debian.org/debian-lts-announce/2018/11/msg00038.html (mailing-list, Mailing List, Third Party Advisory)
bugzilla.redhat.com/show_bug.cgi (VDB Entry, Third Party Advisory, Issue Tracking)

Frequently asked questions

What is CVE-2016-4439?: CVE-2016-4439 is a medium-severity vulnerability in Qemu, classified under Improper Restriction of Operations within the Bounds of a Memory Buffer. CVSS score: 6.7/10. Published 2016-05-20.
How severe is CVE-2016-4439?: Medium severity. CVSS v3 base score is 6.7 out of 10.