# CVE-2026-77159: Libvirt: unsafe chown in qemutpmemulatorpreparehost() allows arbitrary file ownership change via symlink

Status: published. Published: 2026-09-11. Updated: 2026-11-06.

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.

## Remediation

- workaround: On Red Hat Enterprise Linux, SELinux in enforcing mode (the default) confines the swtpm process to the swtpm_t domain, which restricts the creation of symlinks to arbitrary file types and limits the scope of any ownership change, reducing the practical impact of this flaw. Ensure SELinux is not disabled or set to permissive mode. (source: CNA: redhat)

## Affected products and versions

- Red Hat / Red Hat Enterprise Linux 10 (libvirt): Version range not reported. Source: CNA: redhat
- Red Hat / Red Hat Enterprise Linux 6 (libvirt): Version range not reported. Source: CNA: redhat
- Red Hat / Red Hat Enterprise Linux 7 (libvirt): Version range not reported. Source: CNA: redhat
- Red Hat / Red Hat Enterprise Linux 8 (virt:rhel/libvirt): Version range not reported. Source: CNA: redhat
- Red Hat / Red Hat Enterprise Linux 9 (libvirt): Version range not reported. Source: CNA: redhat

## Severity and prioritization

- CVSS 3.1: 5.5 (medium); CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:H/A:N; source: CNA: redhat

- CISA KEV: No listing in collected sources

- EPSS: 0.16% as of 2026-11-05; percentile 5.46%

- SSVC: exploitation poc; automatable no; technical impact partial; source ADP: CISA-ADP

- Weaknesses: CWE-61

## Exploit evidence

- exploit: https://gitlab.com/libvirt/libvirt/-/work_items/909 (ADP: CISA-ADP)

## References

- https://access.redhat.com/security/cve/CVE-2026-77159 (CNA: redhat; vdb-entry, x_refsource_REDHAT)

- https://bugzilla.redhat.com/show_bug.cgi?id=2531811 (CNA: redhat; issue-tracking, x_refsource_REDHAT)

- https://gitlab.com/libvirt/libvirt/-/work_items/909 (CNA: redhat)

- https://gitlab.com/libvirt/libvirt/-/work_items/909 (ADP: CISA-ADP; exploit)

## Provenance

- CNA: redhat: https://www.cve.org/CVERecord?id=CVE-2026-77159; retrieved 2026-11-06; source updated 2026-11-06

- FIRST EPSS: https://api.first.org/data/v1/epss?cve=CVE-2026-77159; retrieved 2026-11-06; source updated Not reported

Revision: b6386c32aa33d8558c404a4c0f6dd422711e92ad4032e9f470a083f4082acc96

Canonical: https://y2.dev/cve/CVE-2026-77159

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