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Fencer Vulns
high 8.2

CVE-2020-35517 json

A flaw was found in qemu.

published 2021-01-28 5 y ago modified 2026-06-17 4 mo ago also EUVD-2020-23184

cvss
8.2
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 43%
public exploits
0
none known

Summary

A flaw was found in qemu. A host privilege escalation issue was found in the virtio-fs shared file system daemon where a privileged guest user is able to create a device special file in the shared directory and use it to r/w access host devices.

Patch / fix

  • qemu Debian 14, Debian 13, Debian 12 1:5.2+dfsg-5

debian advisories DEBIAN-CVE-2020-35517

  • SLOF advanced virtualization 8.3 20200717-1.gite18ddad8.module+el8.3.0+7638+07cf13d2
  • hivex advanced virtualization 8.3 1.3.18-20.module+el8.3.0+6124+819ee737
  • netcf advanced virtualization 8.3 0.2.8-12.module+el8.3.0+6124+819ee737
  • swtpm advanced virtualization 8.3 0.4.2-1.20201201git2df14e3.module+el8.3.1+9074+e34e3b04
  • libnbd advanced virtualization 8.3 1.4.0-2.module+el8.3.0+7998+6ff5e5ab
  • nbdkit advanced virtualization 8.3 1.22.0-2.module+el8.3.0+8203+18ecf00e
  • libtpms advanced virtualization 8.3 0.7.4-1.20201106git2452a24dab.module+el8.3.1+8772+a3fdeccd
  • libvirt advanced virtualization 8.3 6.6.0-13.module+el8.3.1+9548+0a8fede5

red hat advisories RHBA-2021:0639RHSA-2021:0743RHSA-2021:0711

  • hivex AlmaLinux 8 1.3.18-20.module_el8.3.0+2048+e7a0a3ea
  • 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
  • netcf AlmaLinux 8 0.2.8-12.module_el8.3.0+2048+e7a0a3ea
  • libnbd AlmaLinux 8 1.2.2-1.module_el8.5.0+2608+72063365
  • libnbd AlmaLinux 8 1.2.2-1.module_el8.3.0+2048+e7a0a3ea
  • nbdkit AlmaLinux 8 1.16.2-4.module_el8.5.0+2608+72063365
  • libvirt AlmaLinux 8 6.0.0-28.module_el8.3.0+2048+e7a0a3ea

almalinux advisories ALSA-2021:0711

  • hivex Rocky Linux 8 1.3.18-20.module+el8.4.0+534+4680a14e
  • 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
  • seabios Rocky Linux 8 1.13.0-2.module+el8.4.0+534+4680a14e
  • sgabios Rocky Linux 8 1:0.20170427git-3.module+el8.7.0+1084+97b81f61

rocky linux advisories RLSA-2021:0711

  • qemu Alpine 3.24, Alpine 3.23, Alpine 3.22 +6 more 5.2.0-r0

alpine advisories ALPINE-CVE-2020-35517

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-2020-35517 updated cvss 7.5

QEMU: virtiofsd: potential privileged host device access from guest

  • 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, seabios 1.13.0-2.module+el8.2.1+7284+aa32a2c4, libiscsi 1.18.0-8.module+el8.2.0+4793+b09dd2fb, +45 more
    fixed: vendor fix RHSA-2021:0743
  • Red Hat Advanced Virtualization CodeReady Builder for RHEL 8.3.1 libnbd 1.4.0-2.module+el8.3.0+7998+6ff5e5ab, netcf 0.2.8-12.module+el8.3.0+6124+819ee737, hivex 1.3.18-20.module+el8.3.0+6124+819ee737, nbdfuse 1.4.0-2.module+el8.3.0+7998+6ff5e5ab, libvirt 6.6.0-13.module+el8.3.1+9548+0a8fede5, seabios 1.14.0-1.module+el8.3.0+7638+07cf13d2, +40 more
    fixed: vendor fix RHBA-2021:0639
  • 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, seabios 1.13.0-2.module+el8.2.1+7284+aa32a2c4, +96 more
    fixed: vendor fix RHSA-2021:0743
  • Red Hat Advanced Virtualization for RHEL 8.3.1 libnbd 1.4.0-2.module+el8.3.0+7998+6ff5e5ab, netcf 0.2.8-12.module+el8.3.0+6124+819ee737, hivex 1.3.18-20.module+el8.3.0+6124+819ee737, nbdfuse 1.4.0-2.module+el8.3.0+7998+6ff5e5ab, nbdkit 1.22.0-2.module+el8.3.0+8203+18ecf00e, libvirt 6.6.0-13.module+el8.3.1+9548+0a8fede5, +103 more
    fixed: vendor fix RHBA-2021:0639
  • 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, hivex 1.3.18-20.module+el8.3.0+6423+e4cb6418, nbdfuse 1.2.2-1.module+el8.3.0+7353+9de0a3cc, libvirt 6.0.0-28.module+el8.3.0+7827+5e65edd7, seabios 1.13.0-2.module+el8.3.0+7353+9de0a3cc, +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, hivex 1.3.18-20.module+el8.3.0+6423+e4cb6418, nbdfuse 1.2.2-1.module+el8.3.0+7353+9de0a3cc, nbdkit 1.16.2-4.module+el8.3.0+6922+fd575af8, libvirt 6.0.0-28.module+el8.3.0+7827+5e65edd7, +88 more
    fixed: vendor fix RHSA-2021:0711
  • 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-img-rhev, +9 more
    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

0.51% chance of exploitation in the next 30 days, higher than 43% of all scored CVEs (FIRST EPSS, 2026-11-08).

Exploits and checks

  • openwall.com https://www.openwall.com/lists/oss-security/2021/01/22/1 referenced PoC, tagged "exploit" by a source, unverified
  • lists.gnu.org https://lists.gnu.org/archive/html/qemu-devel/2021-01/msg05461.html referenced PoC, tagged "exploit" by a source, unverified

CVSS scores

assigned by version score vector
NVD 3.1 8.2 CVSS:3.1/AV:L/AC:L/PR:H/UI:N/S:C/C:H/I:H/A:H
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-269 Improper Privilege Management

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.