CVE-2026-46123
HighCVSS 7.7Exploitation Probability (EPSS)
Low risk4th percentile - higher than 4% of all known CVEs
Summary
A vulnerability has been identified in the Linux kernel's Bluetooth module that allows improper processing of buffer length, potentially leading to exposure of uninitialized kernel memory. The issue occurs in the virtbt_rx_work() function, where the buffer length is not properly validated.
Risk Assessment
An attacker could exploit this vulnerability to read dangerous data from kernel memory, potentially leading to privilege escalation or system destabilization. If exploited, the organization may face serious security issues.
Recommendation
It is recommended to update the Linux kernel to a version that includes fixes for this vulnerability. Additionally, implementing kernel log monitoring mechanisms is advised to minimize the risk of unauthorized access to memory.
Original NVD description (English source)
In the Linux kernel, the following vulnerability has been resolved: Bluetooth: virtio_bt: clamp rx length before skb_put virtbt_rx_work() calls skb_put(skb, len) where len comes directly from virtqueue_get_buf() with no validation against the buffer we posted to the device. The RX skb is allocated in virtbt_add_inbuf() and exposed to virtio as exactly 1000 bytes via sg_init_one(). Checking len against skb_tailroom(skb) is not sufficient because alloc_skb() can leave more tailroom than the 1000 bytes actually handed to the device. A malicious or buggy backend can therefore report used.len between 1001 and skb_tailroom(skb), causing skb_put() to include uninitialized kernel heap bytes that were never written by the device. The same path also accepts len == 0, in which case skb_put(skb, 0) leaves the skb empty but virtbt_rx_handle() still reads the pkt_type byte from skb->data, consuming uninitialized memory. Define VIRTBT_RX_BUF_SIZE once and reuse it in alloc_skb() and sg_init_one(), and gate virtbt_rx_work() on that same constant so the bound checked matches the buffer actually exposed to the device. Reject used.len == 0 in the same gate so an empty completion can no longer reach virtbt_rx_handle(). Use bt_dev_err_ratelimited() because the length value comes from an untrusted backend that can otherwise flood the kernel log. Same class of bug as commit c04db81cd028 ("net/9p: Fix buffer overflow in USB transport layer"), which hardened the USB 9p transport against unchecked device-reported length.