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Fencer Vulns
medium 5.5

CVE-2026-77159 json

Libvirt: unsafe chown in qemutpmemulatorpreparehost() allows arbitrary file ownership change via symlink

published 2026-09-11 59 d ago modified 2026-11-06 3 d ago also EUVD-2026-76034

cvss
5.5
version 3.1, CNA
cisa kev
Not listed
not in CISA's catalog
epss
0.2%
EPSS 0.2% chance of exploitation in 30 days, percentile 5%
public exploits
0
none known

Summary

A symlink-following flaw was found in libvirt's qemuTPMEmulatorPrepareHost() function. The function uses a path-based chown() on the swtpm logfile without checking for symbolic links. A local attacker with access to the swtpm account can replace the logfile with a symlink, causing libvirtd (running as root) to transfer ownership of an arbitrary file to the swtpm user.

Patch / fix

  • libvirt Debian 14 12.7.0-1

debian advisories DEBIAN-CVE-2026-77159

  • libvirt Ubuntu 22.04 LTS 8.0.0-1ubuntu7.21
  • libvirt Ubuntu 24.04 LTS 10.0.0-2ubuntu8.19
  • libvirt Ubuntu 26.04 LTS 12.0.0-1ubuntu5.5
  • libvirt-hwe Ubuntu 26.04 LTS 12.0.0-1ubuntu5.5

ubuntu advisories UBUNTU-CVE-2026-77159

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

  • libvirt SLES for SAP 15 SP5, SLES 15 SP5-LTSS, SLE Micro 5.5 +2 more 9.0.0-150500.6.29.1
  • libvirt SLES for SAP 15 SP4, SLES 15 SP4-LTSS, SLE Micro 5.4 +3 more 8.0.0-150400.7.17.1
  • libvirt SLE Module for Server Applications 15 SP7, SLE Module for Basesystem 15 SP7 11.0.0-150700.4.27.1
  • libvirt SLES 16.0, Linux Micro 6.2, SLES for SAP applications 16.0 11.4.0-160000.5.1
  • libvirt Linux Micro 6.0 10.0.0-5.1
  • libvirt Linux Micro 6.1 10.0.0-slfo.1.1_3.1
  • libvirt SLES LTSS Extended Security 12 SP5, SLES 12 SP5-LTSS 5.1.0-13.48.1
  • libvirt SLES for SAP 15 SP6, SLES 15 SP6-LTSS 10.0.0-150600.8.18.1

suse advisories SUSE-SU-2026:4141-1SUSE-SU-2026:4010-1SUSE-SU-2026:4009-1SUSE-SU-2026:4004-1SUSE-SU-2026:3939-1SUSE-SU-2026:23460-1

  • libvirt openSUSE Leap 16.0 11.4.0-160000.5.1
  • libvirt openSUSE Tumbleweed 12.6.0-2.1

opensuse advisories openSUSE-SU-2026:21738-1openSUSE-SU-2026:11622-1

  • libvirt Azure Linux 3.0 11.9.0-2

azure linux advisories AZL-101739

Azure Linux vulnerability data, Copyright (c) Microsoft Corporation, from https://github.com/microsoft/AzureLinuxVulnerabilityData via OSV, under the MIT licence; changed: normalised to fixed package versions per release. MIT

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-2026-77159 updated cvss 5.5

libvirt: Unsafe chown in qemuTPMEmulatorPrepareHost() allows arbitrary file ownership change via symlink

  • Red Hat Enterprise Linux 7 libvirt, libvirt-nss, libvirt-libs, libvirt-admin, libvirt-client, libvirt-daemon, +24 more
    affected: workaround, no fix planned “Out of support scope”
  • Red Hat Enterprise Linux 8 libvirt, libvirt-nss, libvirt-libs, libvirt-admin, libvirt-client, libvirt-daemon, +22 more Red Hat Enterprise Linux 9 libvirt, libvirt-nss, libvirt-libs, libvirt-client, libvirt-daemon, libvirt-ssh-proxy, +25 more Red Hat Enterprise Linux 10 libvirt
    affected: workaround, no fix available “Fix deferred”
  • Red Hat Enterprise Linux 6 libvirt, libvirt-client, libvirt-python, libvirt-lock-sanlock
    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

CISA SSVC

Exploitation
Proof of concept is public
Automatable
no
Technical impact
partial
Assessed
54 d ago

Exploit prediction

0.16% chance of exploitation in the next 30 days, higher than 5% of all scored CVEs (FIRST EPSS, 2026-11-08).

Exploits and checks

  • gitlab.com https://gitlab.com/libvirt/libvirt/-/work_items/909 referenced PoC, tagged "exploit" by a source, unverified

CVSS scores

assigned by version score vector
CNA 3.1 5.5 CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:H/A:N

Affected products

  • Red Hat Red Hat Enterprise Linux 10
  • Red Hat Red Hat Enterprise Linux 6
  • Red Hat Red Hat Enterprise Linux 7
  • Red Hat Red Hat Enterprise Linux 8
  • Red Hat Red Hat Enterprise Linux 9

Classification

Weakness
  • CWE-61 UNIX Symbolic Link (Symlink) Following

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.