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Fencer Vulns
medium 5.0

CVE-2020-10761 json

An assertion failure issue was found in the Network Block Device(NBD) Server in all QEMU versions before QEMU 5.0.1.

published 2020-06-09 6 y ago modified 2026-06-17 4 mo ago also EUVD-2020-3177

cvss
5.0
version 3.1, CNA
cisa kev
Not listed
not in CISA's catalog
epss
1.8%
EPSS 1.8% chance of exploitation in 30 days, percentile 78%
public exploits
0
none known

Summary

An assertion failure issue was found in the Network Block Device(NBD) Server in all QEMU versions before QEMU 5.0.1. This flaw occurs when an nbd-client sends a spec-compliant request that is near the boundary of maximum permitted request length. A remote nbd-client could use this flaw to crash the qemu-nbd server resulting in a denial of service.

Patch / fix

  • qemu qemu 5.0.1
  • qemu Debian 14, Debian 13, Debian 12 1:5.0-6

debian advisories DEBIAN-CVE-2020-10761

  • qemu Ubuntu 20.04 LTS 1:4.2-3ubuntu6.4

ubuntu advisories UBUNTU-CVE-2020-10761

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 advanced virtualization 8.2 20191022-3.git899d9883.module+el8.2.0+5449+efc036dd
  • hivex advanced virtualization 8.2 1.3.18-20.module+el8.2.0+5588+63a201c3
  • netcf advanced virtualization 8.2 0.2.8-12.module+el8.2.0+4793+b09dd2fb
  • swtpm advanced virtualization 8.2 0.2.0-2.20200127gitff5a83b.module+el8.2.0+5579+d71178e0
  • libnbd advanced virtualization 8.2 1.2.2-1.module+el8.2.0+5644+32ac38d4
  • nbdkit advanced virtualization 8.2 1.16.2-4.module+el8.2.1+6710+effcb1df
  • libtpms advanced virtualization 8.2 0.7.0-1.20191018gitdc116933b7.module+el8.2.0+4793+b09dd2fb
  • libvirt advanced virtualization 8.2 6.0.0-25.module+el8.2.1+7154+47ffd890

red hat advisories RHBA-2020:3172

  • qemu SLE Module for Server Applications 15 SP2, SLE Module for Basesystem 15 SP2 4.2.1-11.4.4

suse advisories SUSE-SU-2020:2015-1

  • qemu openSUSE Tumbleweed 6.1.0-32.1
  • qemu openSUSE Leap 15.2 4.2.1-lp152.9.3.1
  • qemu-testsuite openSUSE Leap 15.2 4.2.1-lp152.9.3.1
  • qemu-linux-user openSUSE Leap 15.2 4.2.1-lp152.9.3.1

opensuse advisories openSUSE-SU-2024:11287-1openSUSE-SU-2020:1108-1

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-2020-10761 updated cvss 5.0

QEMU: nbd: reachable assertion failure in nbd_negotiate_send_rep_verr via remote client

  • 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
    affected: no fix available
  • Red Hat Advanced Virtualization CodeReady Builder for RHEL 8.2.1 libnbd 1.2.2-1.module+el8.2.0+5644+32ac38d4, netcf 0.2.8-12.module+el8.2.0+4793+b09dd2fb, hivex 1.3.18-20.module+el8.2.0+5588+63a201c3, nbdfuse 1.2.2-1.module+el8.2.0+5644+32ac38d4, libvirt 6.0.0-25.module+el8.2.1+7154+47ffd890, seabios 1.13.0-2.module+el8.2.1+7284+aa32a2c4, +45 more Red Hat Advanced Virtualization for RHEL 8.2.1 libnbd 1.2.2-1.module+el8.2.0+5644+32ac38d4, netcf 0.2.8-12.module+el8.2.0+4793+b09dd2fb, hivex 1.3.18-20.module+el8.2.0+5588+63a201c3, nbdfuse 1.2.2-1.module+el8.2.0+5644+32ac38d4, nbdkit 1.16.2-4.module+el8.2.1+6710+effcb1df, libvirt 6.0.0-25.module+el8.2.1+7154+47ffd890, +96 more
    fixed: vendor fix RHBA-2020:3172
  • Red Hat Enterprise Linux 5 kvm 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 9 qemu-img, qemu-kvm, qemu-kvm-core, qemu-kvm-tools, qemu-pr-helper, qemu-kvm-common, +16 more 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
    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

1.80% chance of exploitation in the next 30 days, higher than 78% of all scored CVEs (FIRST EPSS, 2026-11-08).

CVSS scores

assigned by version score vector
CNA 3.1 5.0 CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:N/I:N/A:L
NVD 3.1 5.0 CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:N/I:N/A:L
NVD 2.0 4.0 AV:N/AC:L/Au:S/C:N/I:N/A:P

Affected products

  • Red Hat QEMU:

Classification

Weakness

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.