What is CVE-2018-20124?

CVE-2018-20124 is a medium-severity vulnerability in Qemu, classified under Out-of-bounds Read. CVSS score: 5.5/10. Published 2018-12-20.

How severe is CVE-2018-20124?

Medium severity. CVSS v3 base score is 5.5 out of 10.

Out-of-bounds Read in Qemu

CVE-2018-20124

hw/rdma/rdma_backend.c in QEMU allows guest OS users to trigger out-of-bounds access via a PvrdmaSqWqe ring element with a large num_sge value.

Vulnerability class: Buffer Overflow

Published 2018-12-20 · last modified 2026-06-17.

CVSS v3 metric

CVSS v3 base score 5.5 (Medium). Vector: CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H.

EPSS exploit prediction

EPSS: 0.005 (39.6th percentile), scored 2026-09-29.

Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 40th percentile — 39.6% 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 14.04, 16.04, 18.04

Weakness classification (CWE)

CWE-125 — Out-of-bounds Read

References

lists.gnu.org/archive/html/qemu-devel/2018-12/msg02822.html (mailing-list, Patch, Third Party Advisory)
www.openwall.com/lists/oss-security/2018/12/18/2 (mailing-list, Patch, Mailing List, Third Party Advisory)
www.securityfocus.com/bid/106290 (VDB Entry, Third Party Advisory, vdb-entry)
usn.ubuntu.com/3923-1/ (vendor-advisory, Third Party Advisory)

Frequently asked questions

What is CVE-2018-20124?: CVE-2018-20124 is a medium-severity vulnerability in Qemu, classified under Out-of-bounds Read. CVSS score: 5.5/10. Published 2018-12-20.
How severe is CVE-2018-20124?: Medium severity. CVSS v3 base score is 5.5 out of 10.