{"id":"AZL-89096","summary":"CVE-2026-46123 affecting package kernel for versions less than 6.6.141.1-1","details":"In the Linux kernel, the following vulnerability has been resolved:\n\nBluetooth: virtio_bt: clamp rx length before skb_put\n\nvirtbt_rx_work() calls skb_put(skb, len) where len comes directly\nfrom virtqueue_get_buf() with no validation against the buffer we\nposted to the device. The RX skb is allocated in virtbt_add_inbuf()\nand exposed to virtio as exactly 1000 bytes via sg_init_one().\n\nChecking len against skb_tailroom(skb) is not sufficient because\nalloc_skb() can leave more tailroom than the 1000 bytes actually\nhanded to the device. A malicious or buggy backend can therefore\nreport used.len between 1001 and skb_tailroom(skb), causing skb_put()\nto include uninitialized kernel heap bytes that were never written by\nthe device.\n\nThe same path also accepts len == 0, in which case skb_put(skb, 0)\nleaves the skb empty but virtbt_rx_handle() still reads the pkt_type\nbyte from skb-\u003edata, consuming uninitialized memory.\n\nDefine VIRTBT_RX_BUF_SIZE once and reuse it in alloc_skb() and\nsg_init_one(), and gate virtbt_rx_work() on that same constant so\nthe bound checked matches the buffer actually exposed to the device.\nReject used.len == 0 in the same gate so an empty completion can\nno longer reach virtbt_rx_handle().\n\nUse bt_dev_err_ratelimited() because the length value comes from an\nuntrusted backend that can otherwise flood the kernel log.\n\nSame class of bug as commit c04db81cd028 (\"net/9p: Fix buffer\noverflow in USB transport layer\"), which hardened the USB 9p\ntransport against unchecked device-reported length.","modified":"2026-08-28T17:48:10.277555589Z","published":"2026-05-28T10:16:27Z","upstream":["CVE-2026-46123"],"references":[{"type":"WEB","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-46123"}],"affected":[{"package":{"name":"kernel","ecosystem":"Azure Linux:3","purl":"pkg:rpm/azure-linux/kernel"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"6.6.141.1-1"}]}],"database_specific":{"source":"https://github.com/microsoft/AzureLinuxVulnerabilityData/blob/main/osv/AZL-89096.json"}}],"schema_version":"1.9.0"}