CVE-2020-25637: Double Free

A double free memory issue was found to occur in the libvirt API, in versions before 6.8.0, responsible for requesting information about network interfaces of a running QEMU domain. This flaw affects the polkit access control driver. Specifically, clients connecting to the read-write socket with limited ACL permissions could use this flaw to crash the libvirt daemon, resulting in a denial of service, or potentially escalate their privileges on the system. The highest threat from this vulnerability is to data confidentiality and integrity as well as system availability.

A double free vulnerability was found in libvirt while requesting information about the network interfaces of a running domain. The flaw lies in qemuAgentGetInterfaces() in qemu/qemuagent.c. More specifically, this function interacts with the guest agent and receives JSON data from the agent that contains network interface information. It enumerates the interfaces one by one, using a pointer to a pointers to hold a split interface name (ifname). At some point in every iteration ifname is free'd. If an error occurs right after this, there is a 'goto error', the error handler at this label will free ifname again, leading to a double free. Depending on the ability of the attacker to control and shape the heap state when the second free happens, this flaw may be exploited to achieve code execution.

— Red Hat