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Fencer Vulns
medium 5.7

CVE-2021-3409 json

The patch for CVE-2020-17380/CVE-2020-25085 was found to be ineffective, thus making QEMU vulnerable to the out-of-bounds read/write access…

published 2021-03-23 5 y ago modified 2026-06-17 4 mo ago also EUVD-2021-26737

cvss
5.7
version 3.1, NVD
cisa kev
Not listed
not in CISA's catalog
epss
0.5%
EPSS 0.5% chance of exploitation in 30 days, percentile 42%
public exploits
0
none known

Summary

The patch for CVE-2020-17380/CVE-2020-25085 was found to be ineffective, thus making QEMU vulnerable to the out-of-bounds read/write access issues previously found in the SDHCI controller emulation code. This flaw allows a malicious privileged guest to crash the QEMU process on the host, resulting in a denial of service or potential code execution. QEMU up to (including) 5.2.0 is affected by this.

Patch / fix

  • qemu Debian 14, Debian 13, Debian 12 1:5.2+dfsg-10

debian advisories DEBIAN-CVE-2021-3409

  • qemu Ubuntu 18.04 LTS 1:2.11+dfsg-1ubuntu7.37
  • qemu Ubuntu 20.04 LTS 1:4.2-3ubuntu6.17
  • qemu Ubuntu Pro 14.04 LTS 2.0.0+dfsg-2ubuntu1.47+esm6
  • qemu Ubuntu Pro 16.04 LTS 1:2.5+dfsg-5ubuntu10.51+esm4

ubuntu advisories UBUNTU-CVE-2021-3409

Ubuntu security data © Canonical Ltd., from https://github.com/canonical/ubuntu-security-notices via OSV; changed: normalised to fixed package versions per release. CC BY-SA 4.0

  • qemu SLES for SAP 12 SP5, SLES 12 SP5 3.1.1.1-66.1
  • qemu SLES for SAP 15 SP1, SLES 15 SP1-LTSS, SLES 15 SP1-BCL +4 more 3.1.1.1-150100.80.43.2
  • qemu SLES for SAP 15 SP2, SLES 15 SP2-LTSS, SLES 15 SP2-BCL +8 more 4.2.1-150200.69.1
  • qemu SLE Module for Server Applications 15 SP3, SLE Module for Basesystem 15 SP3 5.2.0-17.1

suse advisories SUSE-SU-2023:0761-1SUSE-SU-2022:3768-1SUSE-SU-2022:3594-1SUSE-SU-2021:1942-1

  • qemu openSUSE Leap 15.3 5.2.0-17.1

opensuse advisories openSUSE-SU-2021:1942-1

  • qemu Alpine 3.24, Alpine 3.23, Alpine 3.22 +6 more 6.0.0-r1

alpine advisories ALPINE-CVE-2021-3409

Alpine secdb © Alpine Linux, from https://secdb.alpinelinux.org via OSV; changed: normalised to fixed package versions per release. CC BY-SA 4.0

Vendor advisories

What the vendors themselves say about their products: affected, fixed or not affected, and what to do.

red hat product security vex CVE-2021-3409 updated cvss 5.7

QEMU: sdhci: incomplete fix for CVE-2020-17380/CVE-2020-25085

  • Red Hat Enterprise Linux 5 kvm, xen Red Hat Enterprise Linux 6 qemu-img, qemu-kvm, qemu-kvm-tools, qemu-guest-agent, qemu-guest-agent-win32 Red Hat Enterprise Linux 7 qemu-img, qemu-kvm, libcacard, qemu-img-ma, qemu-kvm-ma, qemu-kvm-rhev, +6 more Red Hat Enterprise Linux 8 qemu-img, qemu-kvm, qemu-kvm-core, qemu-kvm-tests, qemu-kvm-common, qemu-guest-agent, +8 more Red Hat Enterprise Linux 8 Advanced Virtualization qemu-img, qemu-kvm, qemu-kiwi, qemu-kvm-core, qemu-kvm-tests, qemu-kvm-common, +9 more Red Hat OpenStack Platform 10 (Newton) qemu-img-rhev, qemu-kvm-rhev, qemu-kvm-tools-rhev, qemu-kvm-common-rhev
    +1 more products
    Red Hat OpenStack Platform 13 (Queens) qemu-img-rhev, qemu-kvm-rhev, qemu-kvm-tools-rhev, qemu-kvm-common-rhev
    not affected: vulnerable code not present

Red Hat CSAF VEX © Red Hat, Inc., from https://security.access.redhat.com/data/csaf/v2/vex/; changed: reduced to product statuses and remediations. CC BY 4.0 · csaf

Exploit prediction

0.49% chance of exploitation in the next 30 days, higher than 42% of all scored CVEs (FIRST EPSS, 2026-11-08).

CVSS scores

assigned by version score vector
NVD 3.1 5.7 CVSS:3.1/AV:L/AC:L/PR:H/UI:N/S:C/C:L/I:L/A:L
NVD 2.0 4.6 AV:L/AC:L/Au:N/C:P/I:P/A:P

Affected products

  • n/a QEMU

Classification

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

References

Sources

Fencer Vulns keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.