A flaw was found in the QEMU Guest Agent (qga). A local unprivileged user can exploit a vulnerability in the guest-ssh-add-authorized-keys command handler by manipulating symbolic links. This can occur either through a deterministic directory-symlink bypass or a Time-of-Check to Time-of-Use (TOCTOU) file-symlink race. Successful exploitation allows the attacker to gain ownership of arbitrary root-owned files or directories, leading to root access. This vulnerability requires an external management layer (e.g., libvirt) to trigger the affected code path.
Weakness
The product, when opening a file or directory, does not sufficiently account for when the file is a symbolic link that resolves to a target outside of the intended control sphere. This could allow an attacker to cause the product to operate on unauthorized files.
Affected Software
| Name | Vendor | Start Version | End Version |
|---|---|---|---|
| Red Hat Enterprise Linux 9 | RedHat | qemu-kvm-17:10.1.0-17.el9_8.9 | * |
| Qemu | Ubuntu | devel | * |
| Qemu | Ubuntu | esm-infra-legacy/trusty | * |
| Qemu | Ubuntu | esm-infra-legacy/xenial | * |
| Qemu | Ubuntu | esm-infra/bionic | * |
| Qemu | Ubuntu | esm-infra/focal | * |
| Qemu | Ubuntu | jammy | * |
| Qemu | Ubuntu | noble | * |
| Qemu | Ubuntu | resolute | * |
| Qemu | Ubuntu | stonking | * |
| Qemu-hwe | Ubuntu | devel | * |
| Qemu-hwe | Ubuntu | resolute | * |
| Qemu-hwe | Ubuntu | stonking | * |
Potential Mitigations
- Follow the principle of least privilege when assigning access rights to entities in a software system.
- Denying access to a file can prevent an attacker from replacing that file with a link to a sensitive file. Ensure good compartmentalization in the system to provide protected areas that can be trusted.