What is CVE-2020-15863?

CVE-2020-15863 is a medium-severity vulnerability in Qemu, classified under Out-of-bounds Write. CVSS score: 5.3/10. Published 2020-07-28.

How severe is CVE-2020-15863?

Medium severity. CVSS v3 base score is 5.3 out of 10.

Buffer overflow in Qemu

CVE-2020-15863

hw/net/xgmac.c in the XGMAC Ethernet controller in QEMU before 07-20-2020 has a buffer overflow. This occurs during packet transmission and affects the highbank and midway emulated machines. A guest user or process could use this flaw to crash the QEMU process on the host, resulting in a denial of service or potential privileged code execution. This was fixed in commit 5519724a13664b43e225ca05351c60b4468e4555.

Vulnerability class: Buffer Overflow

Published 2020-07-28 · last modified 2026-06-17.

CVSS v3 metric

CVSS v3 base score 5.3 (Medium). Vector: CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:C/C:L/I:L/A:L.

EPSS exploit prediction

EPSS: 0.005 (38.7th percentile), scored 2026-09-29.

Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 39th percentile — 38.7% 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 — versions 5.1.0
Canonical Ubuntu Linux — versions 16.04, 18.04, 20.04
Debian Linux — versions 10.0

Weakness classification (CWE)

CWE-787 — Out-of-bounds Write

References

lists.nongnu.org/archive/html/qemu-devel/2020-07/msg03497.html (Patch, Mailing List, Third Party Advisory)
www.openwall.com/lists/oss-security/2020/07/22/1 (Patch, Mailing List, Third Party Advisory)
git.qemu.org/
lists.nongnu.org/archive/html/qemu-devel/2020-07/msg05745.html (Patch, Mailing List, Third Party Advisory)
usn.ubuntu.com/4467-1/ (vendor-advisory, Third Party Advisory)
www.debian.org/security/2020/dsa-4760 (vendor-advisory, Third Party Advisory)
lists.opensuse.org/opensuse-security-announce/2020-10/msg00024.html (vendor-advisory, Mailing List, Third Party Advisory)
security.gentoo.org/glsa/202208-27 (vendor-advisory, Third Party Advisory)

Frequently asked questions

What is CVE-2020-15863?: CVE-2020-15863 is a medium-severity vulnerability in Qemu, classified under Out-of-bounds Write. CVSS score: 5.3/10. Published 2020-07-28.
How severe is CVE-2020-15863?: Medium severity. CVSS v3 base score is 5.3 out of 10.