The vulnerability in the Linux kernel’s virtio vsock transport lets a malicious peer advertise an arbitrarily large send buffer size. This forces the host or guest to reserve an equivalent amount of sk_buff memory, causing slab allocation to grow uncontrollably. An attacker can therefore exhaust kernel memory and trigger out‑of‑memory conditions or make the system unresponsive. The flaw is a classic case of uncontrolled resource consumption.

All Linux kernel builds that include virtio vsock support, such as typical KVM/QEMU hosts and their guests, are affected by this issue in versions before the patch that caps the TX credit to the lower of the peer’s buffer and the local limit. Kernel releases that integrate the virtio_transport_tx_buf_size change, including 6.19 rc6 and later, have removed the flaw.

The CVSS base score of 5.5 indicates moderate severity, while an EPSS value of less than 1% points to a low likelihood of exploitation. The vulnerability is not listed in the CISA KEV catalog. Exploitation requires control over a virtual machine or host to open many vsock connections advertising large buffers; such activity can be detected and limited with cgroups or memory constraints. Successful exploitation can consume tens of gigabytes of memory, potentially leading to kernel OOM kills and downtime.