Cloud hypervisor is a Virtual Machine Monitor for Cloud workloads. This vulnerability allows users to close arbitrary open file descriptors in the Cloud Hypervisor process via sending malicious HTTP request through the HTTP API socket. As a result, the Cloud Hypervisor process can be easily crashed, causing Deny-of-Service (DoS). This can also be a potential Use-After-Free (UAF) vulnerability. Users require to have the write access to the API socket file to trigger this vulnerability. Impacted versions of Cloud Hypervisor include upstream main branch, v31.0, and v30.0. The vulnerability was initially detected by our http_api_fuzzer
via oss-fuzz. This issue has been addressed in versions 30.1 and 31.1. Users unable to upgrade may mitigate this issue by ensuring the write access to the API socket file is granted to trusted users only.
Referencing memory after it has been freed can cause a program to crash, use unexpected values, or execute code.
Name | Vendor | Start Version | End Version |
---|---|---|---|
Cloud_hypervisor | Cloudhypervisor | 30.0 (including) | 30.0 (including) |
Cloud_hypervisor | Cloudhypervisor | 31.1 (including) | 31.1 (including) |
The use of previously-freed memory can have any number of adverse consequences, ranging from the corruption of valid data to the execution of arbitrary code, depending on the instantiation and timing of the flaw. The simplest way data corruption may occur involves the system’s reuse of the freed memory. Use-after-free errors have two common and sometimes overlapping causes:
In this scenario, the memory in question is allocated to another pointer validly at some point after it has been freed. The original pointer to the freed memory is used again and points to somewhere within the new allocation. As the data is changed, it corrupts the validly used memory; this induces undefined behavior in the process. If the newly allocated data happens to hold a class, in C++ for example, various function pointers may be scattered within the heap data. If one of these function pointers is overwritten with an address to valid shellcode, execution of arbitrary code can be achieved.