Skip to content
Fencer Vulns
low 3.8

CVE-2021-3592 json

An invalid pointer initialization issue was found in the SLiRP networking implementation of QEMU.

published 2021-06-15 5 y ago modified 2026-06-17 4 mo ago also EUVD-2021-26899

cvss
3.8
version 3.1, NVD
cisa kev
Not listed
not in CISA's catalog
epss
0.3%
EPSS 0.3% chance of exploitation in 30 days, percentile 25%
public exploits
0
none known

Summary

An invalid pointer initialization issue was found in the SLiRP networking implementation of QEMU. The flaw exists in the bootp_input() function and could occur while processing a udp packet that is smaller than the size of the 'bootp_t' structure. A malicious guest could use this flaw to leak 10 bytes of uninitialized heap memory from the host. The highest threat from this vulnerability is to data confidentiality. This flaw affects libslirp versions prior to 4.6.0.

Patch / fix

  • libslirp_project libslirp 4.6.0
  • qemu Debian 14, Debian 13, Debian 12 1:4.1-2
  • libslirp Debian 14, Debian 13, Debian 12 4.6.1-1

debian advisories DEBIAN-CVE-2021-3592

  • qemu Ubuntu 18.04 LTS 1:2.11+dfsg-1ubuntu7.37
  • libslirp Ubuntu 20.04 LTS 4.1.0-2ubuntu2.2
  • libslirp Ubuntu 22.04 LTS 4.6.1-1
  • qemu Ubuntu Pro 14.04 LTS 2.0.0+dfsg-2ubuntu1.47+esm4
  • qemu Ubuntu Pro 16.04 LTS 1:2.5+dfsg-5ubuntu10.51+esm3

ubuntu advisories UBUNTU-CVE-2021-3592

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

  • SLOF RHEL 8 20191022-3.git899d9883.module+el8.3.0+6423+e4cb6418
  • hivex RHEL 8 1.3.18-21.module+el8.5.0+10709+b3edb581
  • netcf RHEL 8 0.2.8-12.module+el8.1.0+4066+0f1aadab
  • libnbd RHEL 8 1.2.2-1.module+el8.3.0+7353+9de0a3cc
  • nbdkit RHEL 8 1.16.2-4.module+el8.3.0+6922+fd575af8
  • libvirt RHEL 8 6.0.0-37.module+el8.5.0+12162+40884dd2
  • nbdfuse RHEL 8 1.2.2-1.module+el8.3.0+7353+9de0a3cc
  • seabios RHEL 8 1.13.0-2.module+el8.3.0+7353+9de0a3cc

red hat advisories RHSA-2021:4191

  • libslirp SLE Module for Server Applications 15 SP4, SLE Module for Server Applications 15 SP3, SLE Micro 5.2 +3 more 4.3.1-150300.6.2
  • libslirp SLE Module for Server Applications 15 SP3, SLE Micro 5.2, SLE Micro 5.1 +2 more 4.3.1-150300.2.7.1
  • xen SLES 12 SP2-BCL 4.7.6_16-43.79.5
  • xen SLES for SAP 12 SP3, SLES 12 SP3-LTSS, SLES 12 SP3-BCL +3 more 4.9.4_20-3.91.1
  • xen SLES for SAP 12 SP4, SLES 12 SP4-LTSS, OpenStack Cloud Crowbar 9 +1 more 4.11.4_20-2.60.1
  • xen SLES for SAP 12 SP5, SLES 12 SP5, SLE Software Development Kit 12 SP5 4.12.4_12-3.49.1
  • kvm SLE Point of Sale 11 SP3 1.4.2-53.41.1
  • qemu SLES for SAP 15 SP1, SLES 15 SP1-LTSS, SLES 15 SP1-BCL +6 more 3.1.1.1-9.30.2

suse advisories SUSE-SU-2022:1730-1SUSE-SU-2022:1465-1SUSE-SU-2021:14848-1SUSE-SU-2021:3322-1SUSE-SU-2021:2957-1SUSE-SU-2021:2955-1

  • libslirp openSUSE Tumbleweed 4.7.0+44-3.1
  • qemu openSUSE Leap 15.2 4.2.1-lp152.9.20.1
  • qemu-testsuite openSUSE Leap 15.2 4.2.1-lp152.9.20.1
  • qemu-linux-user openSUSE Leap 15.2 4.2.1-lp152.9.20.1
  • qemu openSUSE Leap 15.3 3.1.1.1-9.30.2
  • qemu openSUSE Leap 15.3 4.2.1-11.25.2

opensuse advisories openSUSE-SU-2024:12529-1openSUSE-SU-2021:1202-1openSUSE-SU-2021:2591-1openSUSE-SU-2021:2474-1

  • hivex AlmaLinux 8 1.3.18-21.module_el8.5.0+2608+72063365
  • netcf AlmaLinux 8 0.2.8-12.module_el8.5.0+2608+72063365
  • netcf AlmaLinux 8 0.2.8-12.module_el8.6.0+2880+7d9e3703
  • libnbd AlmaLinux 8 1.2.2-1.module_el8.5.0+2608+72063365
  • nbdkit AlmaLinux 8 1.16.2-4.module_el8.5.0+2608+72063365
  • libvirt AlmaLinux 8 6.0.0-37.module_el8.5.0+2608+72063365
  • nbdfuse AlmaLinux 8 1.2.2-1.module_el8.5.0+2608+72063365
  • seabios AlmaLinux 8 1.13.0-2.module_el8.5.0+2608+72063365

almalinux advisories ALSA-2021:4191

  • hivex Rocky Linux 8 1.3.18-21.module+el8.4.0+642+7e26f5e1
  • hivex Rocky Linux 8 1.3.18-21.module+el8.5.0+670+c4aa478c
  • netcf Rocky Linux 8 0.2.8-12.module+el8.7.0+1084+97b81f61
  • netcf Rocky Linux 8 0.2.8-12.module+el8.4.0+534+4680a14e
  • netcf Rocky Linux 8 0.2.8-12.module+el8.6.0+847+b490afdd
  • libnbd Rocky Linux 8 1.2.2-1.module+el8.4.0+534+4680a14e
  • nbdkit Rocky Linux 8 1.16.2-4.module+el8.4.0+534+4680a14e
  • libvirt Rocky Linux 8 6.0.0-37.module+el8.5.0+670+c4aa478c

rocky linux advisories RLSA-2021:4191

  • libslirp Alpine 3.24, Alpine 3.23, Alpine 3.22 +8 more 4.6.0-r0

alpine advisories ALPINE-CVE-2021-3592

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

  • libslirp Arch Linux 4.6.0-1

arch linux advisories AVG-2073

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-2021-3592 updated cvss 3.8

QEMU: slirp: invalid pointer initialization may lead to information disclosure (bootp)

  • 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
    affected: no fix planned “Out of support scope”
  • Red Hat Enterprise Linux 8 libslirp Red Hat Enterprise Linux 8 Advanced Virtualization qemu-img, qemu-kvm, qemu-kiwi, qemu-kvm-core, qemu-kvm-tests, qemu-kvm-common, +9 more
    affected: no fix available “Fix deferred”
  • Red Hat Enterprise Linux 9 qemu-img, qemu-kvm, qemu-kvm-core, qemu-kvm-tools, qemu-pr-helper, qemu-kvm-common, +16 more
    affected: no fix available
  • Red Hat OpenStack Platform 10 (Newton) qemu-img-rhev, qemu-kvm-rhev, qemu-kvm-tools-rhev, qemu-kvm-common-rhev Red Hat OpenStack Platform 13 (Queens) qemu-img-rhev, qemu-kvm-rhev, qemu-kvm-tools-rhev, qemu-kvm-common-rhev
    affected: no fix planned “Out of support scope”
  • Red Hat CodeReady Linux Builder (v. 8) libnbd 1.2.2-1.module+el8.3.0+7353+9de0a3cc, netcf 0.2.8-12.module+el8.1.0+4066+0f1aadab, nbdfuse 1.2.2-1.module+el8.3.0+7353+9de0a3cc, hivex 1.3.18-21.module+el8.5.0+10709+b3edb581, seabios 1.13.0-2.module+el8.3.0+7353+9de0a3cc, libiscsi 1.18.0-8.module+el8.1.0+4066+0f1aadab, +39 more Red Hat Enterprise Linux AppStream (v. 8) libnbd 1.2.2-1.module+el8.3.0+7353+9de0a3cc, netcf 0.2.8-12.module+el8.1.0+4066+0f1aadab, nbdfuse 1.2.2-1.module+el8.3.0+7353+9de0a3cc, nbdkit 1.16.2-4.module+el8.3.0+6922+fd575af8, hivex 1.3.18-21.module+el8.5.0+10709+b3edb581, seabios 1.13.0-2.module+el8.3.0+7353+9de0a3cc, +88 more
    fixed: vendor fix RHSA-2021:4191
  • Red Hat Enterprise Linux 9 libslirp
    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

0.33% chance of exploitation in the next 30 days, higher than 25% of all scored CVEs (FIRST EPSS, 2026-11-08).

CVSS scores

assigned by version score vector
NVD 3.1 3.8 CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:C/C:L/I:N/A:N
NVD 2.0 2.1 AV:L/AC:L/Au:N/C:P/I:N/A:N

Affected products

  • n/a QEMU

Classification

Weakness
  • CWE-824 Access of Uninitialized Pointer

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.