Bug 2513065 (CVE-2026-63622)

Summary: CVE-2026-63622 libvirt: swtpm privilege escalation via symlink following
Product: [Other] Security Response Reporter: OSIDB Bzimport <bzimport>
Component: vulnerabilityAssignee: Product Security <prodsec-ir-bot>
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Priority: high    
Version: unspecifiedCC: rhel-process-autobot, watson-tool-maintainers
Target Milestone: ---Keywords: Security
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Hardware: All   
OS: Linux   
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A flaw was found in libvirt. A local attacker, specifically a process running as the confined `swtpm` user, could exploit a symlink-following vulnerability in the `virFileChownFiles()` function. By planting a symbolic link within the `swtpm` state directory, the attacker could trick the root-level libvirt daemon into changing the ownership of an arbitrary file to the `swtpm` user. This allows for privilege escalation from the `swtpm` sandbox to root-level file ownership control.
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Bug Depends On: 2513834    
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Description OSIDB Bzimport 2026-08-10 09:48:58 UTC 
A symlink-following vulnerability was found in libvirt's virFileChownFiles() function in src/util/virfile.c. This function is called from src/qemu/qemu_tpm.c to change ownership of the swtpm state directory when starting a QEMU domain.

The function used stat() (via virFileIsRegular()) and chown(), both of which follow symlinks. A process running as the confined swtpm user (tss) can plant a symlink inside the swtpm state directory pointing to an arbitrary file. When the root-level libvirt daemon starts the next domain, it calls virFileChownFiles() which follows the symlink and chowns the target file to the tss user. This allows escalation from the swtpm sandbox to root-level file ownership control.

The fix replaces stat()/chown() with lstat()/lchown() to avoid following symlinks on the final path component.

Upstream fix: https://gitlab.com/libvirt/libvirt/-/commit/801160fd414ca2cc402bc01ead09b7ed4c3b8f5b