CVE-2026-77159 Red Hat CVE debrief

Who should care

System administrators and security teams responsible for managing libvirt and ensuring the security of their systems should be aware of this vulnerability and take necessary actions to prevent exploitation. This includes reviewing and updating libvirt configurations, implementing additional security controls to limit local attacker access, and monitoring system logs for suspicious activity related to the swtpm account. Additionally, security teams should

Why it matters

A local attacker with access to the swtpm account can exploit a symlink-following flaw in libvirt's qemuTPMEmulatorPrepareHost() function to transfer ownership of an arbitrary file to the swtpm user, potentially leading to elevation of privileges and data compromise.

• Potential elevation of privileges for local attackers
• Data integrity and confidentiality may be compromised
• System administrators must verify and update libvirt configurations

Technical summary

The qemuTPMEmulatorPrepareHost() function in libvirt 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. This vulnerability is particularly concerning because it allows a local attacker to manipulate file ownership, which could be used to gain further access to the system or to compromise data integrity. The vulnerability is caused by a lack of checks for symbolic links in the qemuTPMEmulatorPrepareHost() function, which allows a local attacker to exploit the flaw and transfer ownership of an

Defensive priority

Medium-priority defensive actions are required to address the symlink-following flaw in libvirt's qemuTPMEmulatorPrepareHost() function.

Recommended defensive actions

• Review and update libvirt configurations to prevent exploitation
• Implement additional security controls to limit local attacker access
• Monitor system logs for suspicious activity related to the swtpm account
• Confirm whether affected product deployments exist in managed environments and assign an owner for follow-up
• Review the supplied official advisory or CVE record to validate affected scope, severity, and vendor guidance
• Plan vendor-supported updates or mitigations through normal change control where exposure is confirmed
• Check relevant monitoring, detection, and logs for exposed assets that need extra review

Evidence notes

The CVE record and NVD entry provide details on the symlink-following flaw in libvirt's qemuTPMEmulatorPrepareHost() function. The flaw is caused by the function's use of a path-based chown() on the swtpm logfile without checking for symbolic links. This allows a local attacker with access to the swtpm account to replace the logfile with a symlink, causing libvirtd (running as root) to transfer ownership of an arbitrary file to the swtpm user. The CVE record and NVD entry provide further information on the vulnerability, including its

Sources and references

Methodology and review provenance

AI-assisted synthesis based on stored public vulnerability evidence. System validation, approval state, and publication status do not by themselves establish human review of this revision. PatchSiren helps prioritize defensive review and does not prove exposure or remediation on any system.