Quick answers
- Is CVE-2026-77159 exploited in the wild?
- No. Junglewise Threat Intelligence has no report of CVE-2026-77159 being exploited in the wild.
- How severe is CVE-2026-77159?
- Medium severity, with a CVSS score of 5.5, published 11 September 2026.
- Which products and versions are affected?
- Libvirt <UNKNOWN>.
- Is there a fix for CVE-2026-77159?
- No fixed version is recorded yet. Check the vendor's advisory in the references below. If you run it, Junglewise drafts a mitigation that fits your setup and applies it once you approve, with senior security engineers behind it.
- How is CVE-2026-77159 attacked?
- It is attacked with local access.
- Am I affected by CVE-2026-77159?
- Check whether you run Libvirt at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.
Technical details
The vulnerability is a symlink-following flaw (CWE-61) in the qemuTPMEmulatorPrepareHost() function within libvirt. The function performs a path-based chown() operation on the swtpm logfile without validating whether the path is a symbolic link. A local attacker with access to the swtpm account can replace the logfile with a symlink pointing to an arbitrary file, causing libvirtd (running as root) to change the ownership of that target file to the swtpm user. Attack requires local access and low privileges (swtpm account access), with no user interaction needed. On Red Hat Enterprise Linux systems with SELinux in enforcing mode (default), the practical impact is significantly reduced due to SELinux confinement of the swtpm process, which restricts symlink creation and limits ownership-change scope.
Affected products
- libvirt libvirt <UNKNOWN>
Timeline
- 2026-09-11: disclosed
- 2026-09-11: advisory: CVE-2026-77159 published