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CVE-2026-63947
Bluetooth: HIDP: fix missing length checks in hidp_input_report()
Published 2026-07-19 (3 months ago) by the Linux kernel CNA. Subsystem net/bluetooth. Debian urgency: not yet assigned.
What to do, per Debian release
Debian's own status for CVE-2026-63947 in every release this site tracks, and what each one means in practice. Every status below is the one the Debian Security Team publishes for this CVE. source
| Release | Status | Version | What this means |
|---|---|---|---|
| Debian 12bookworm | fixed | 6.1.176-1 | Update the kernel and reboot. Fixed in 6.1.176-1. A running kernel keeps the old code until the machine restarts. |
| Debian 13trixie | fixed | 6.12.94-1 | Update the kernel and reboot. Fixed in 6.12.94-1. A running kernel keeps the old code until the machine restarts. |
| Debian 14forky | fixed | 7.0.12-1 | Update the kernel and reboot. Fixed in 7.0.12-1. A running kernel keeps the old code until the machine restarts. |
| Debian unstablesid | fixed | 7.0.12-1 | Update the kernel and reboot. Fixed in 7.0.12-1. A running kernel keeps the old code until the machine restarts. |
The vulnerability
What the bug is
hidp_input_report() reads keyboard and mouse payload data from an skb without first verifying that skb->len contains enough data. hidp_recv_intr_frame() pulls the 1-byte HIDP header before dispatching to hidp_input_report(). If a paired device sends a truncated packet, the handler reads beyond the valid skb data, resulting in an out-of-bounds read of skb data. The OOB bytes may be interpreted as phantom key presses or spurious mouse movement. Replace the open-coded length tracking and pointer arithmetic with skb_pull_data() calls. skb_pull_data() returns NULL if the requested bytes are not present, eliminating the need for a manual size variable and the separate skb->len guard.
Where it lives
The fix touches these files. If the subsystem is one you do not use, the practical exposure is lower, though the package is still the vulnerable one.
net/bluetooth/hidp/core.c
- What this is
- BLUETOOTH SUBSYSTEMMAINTAINERS section matched on net/bluetooth/ · linux-bluetooth@vger.kernel.org · Supported
- Kernel module
- hidp
Check it on the machine
grep -wE 'CONFIG_BT|CONFIG_BT_HIDP' /boot/config-$(uname -r)Reads the booted kernel's own configuration, on the machine and nowhere else. =y is built in, =m is a module, and an is not set line means the code is not there.
lsmod | grep -w hidpPrints a line if that module is loaded right now, and nothing if it is not. One that is not loaded can still be loaded later by anything that needs it.
Show whether Debian builds this, per release
Debian builds this, but not on every flavour. At least one release below builds the code on some of its kernel flavours and not on others, so the answer depends on the architecture and flavour installed.
- bookwormMnot built on amd64/cloud-amd64, arm64/cloud-arm64
- trixie, forky, sidMnot built on amd64/cloud-amd64, arm64/cloud-arm64, s390x/s390x
- M
- a module where it is built at all; some flavours do not build it
- Build switches
- CONFIG_BT, CONFIG_BT_HIDP
- Reads as
- all on means the file is compiled; any one off means it is not.
From the configuration Debian publishes for every kernel flavour it builds. It covers only the architectures Debian ships a linux-config package for, and nothing about a kernel you built yourself. Debian's own status above stays authoritative about the source package.MAINTAINERS kbuild Makefiles Debian linux-config packages
Signals
- Published
- 2026-07-19 (3 months ago)source
- CVSS
- 8.8 high
CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:Hsource recompute it - Attack vector
- adjacent network (AV:A)source
- EPSS
- 0.35%, higher than 26.6% of all CVEssource
- CISA KEV
- not listedthe KEV catalogue
- Debian urgency
- not yet assignedsource
- Subsystem
- net/bluetooth
Upstream fixes
The versions the CNA records as introducing and fixing this, and the commit for each. source
| Introduced | Fixed in | Commit |
|---|---|---|
| 2.6.12 | 5.15.210 | 1f08a90013e1 |
| 2.6.12 | 6.1.176 | cc3832b19f86 |
| 2.6.12 | 6.6.143 | d313683d6ccd |
| 2.6.12 | 6.12.93 | d7d6a81b8dd1 |
| 2.6.12 | 6.18.35 | 6348dfed5b0f |
| 2.6.12 | 7.0.12 | b83dcacd2ec7 |
| 2.6.12 | 7.1 | 2a3ac9ee11db |
Why the CNA scored it this way
Quoted from the kernel CNA's own scoring file, word for word. A highlighted metric carries the most severe value CVSS v3.1 defines for it, which is what pushes the score up. source
- AV:AAttack vector, adjacent network
- The bug is reached when a connected Bluetooth HID peer sends malformed HIDP interrupt (or control DATA) frames over L2CAP ACL; packets traverse HCI → l2cap_recv_acldata() → l2cap_data_channel() → l2cap_sock_recv_cb() → HIDP session thread → hidp_recv_intr_frame()/hidp_process_data() → hidp_input_report(), which is an adjacent Bluetooth attack surface.
- AC:LAttack complexity, low
- Exploitation only requires sending deliberately truncated HIDP input reports on an already-established HIDP/L2CAP session; the attacker fully controls packet length and can trigger the out-of-bounds read reliably on every malformed frame with no race or special memory layout.
- PR:NPrivileges required, none
- The attacker is an external Bluetooth HID device sending L2CAP payloads and needs no Linux account, capability, or namespace privilege; CAP_NET_ADMIN is only required for bluetoothd to register the session, not for the malicious peer to deliver the crafted packets.
- UI:NUser interaction, none
- Once a HIDP session is active, exploitation is automatic from crafted Bluetooth traffic and requires no further victim action; pairing/connection is an attacker prerequisite, not user interaction at exploit time (consistent with prior Bluetooth HIDP CNA scoring such as CVE-2026-23462).
- S:UScope, unchanged
- Impact is confined to kernel HIDP/input handling and forged input events delivered within the same kernel security authority; it does not cross a VM, IOMMU, or sandbox boundary.
- C:HConfidentiality impact, high
- The vulnerable code performs out-of-bounds reads of up to eight keyboard or four mouse payload bytes beyond skb->len, and per CVSS kernel guidance any out-of-bounds read is rated High because adjacent skb tailroom may contain stale packet or kernel heap data observable through phantom key/mouse event side channels.
- I:HIntegrity impact, high
- Out-of-bounds bytes are interpreted as boot-protocol keyboard scancodes and mouse button/movement events, enabling phantom key presses and pointer injection into the system input layer; on laptops, kiosks, automotive consoles, and Android handsets this can forge arbitrary keystrokes/clicks against the active user session.
- A:HAvailability impact, high
- Reading keyboard/mouse payload bytes past valid skb->len is undefined behavior on tightly allocated skbs with no tailroom and can fault the kernel; even when reads stay within tailroom, forged input can repeatedly disrupt session availability on shared/public Bluetooth keyboard deployments, and under the conservative scoring rule this is rated High when crash potential cannot be excluded.