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CVE-2026-63915
nfc: hci: fix out-of-bounds read in HCP header parsing
Published 2026-07-19 (3 months ago) by the Linux kernel CNA. Subsystem net/nfc. Debian urgency: not yet assigned.
What to do, per Debian release
Debian's own status for CVE-2026-63915 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
Both nfc_hci_recv_from_llc() and nci_hci_data_received_cb() read packet->header from skb->data at function entry without first checking that the buffer holds at least one byte. A malicious NFC peer can send a 0-byte HCP frame that passes through the SHDLC layer and reaches these functions, causing an out-of-bounds heap read of packet->header. The same 0-byte frame, if queued as a non-final fragment, also causes the reassembly loop to underflow msg_len to UINT_MAX, triggering skb_over_panic() when the reassembled skb is written. Fix this by adding a pskb_may_pull() check at the entry of each function before packet->header is first accessed. The existing pskb_may_pull() checks before the reassembled hcp_skb is cast to struct hcp_packet remain in place to guard the 2-byte HCP message header.
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/nfc/hci/core.c
net/nfc/nci/hci.c
- What this is
- NFC SUBSYSTEMMAINTAINERS section matched on net/nfc/ · oe-linux-nfc@lists.linux.dev · Maintained
- Kernel module
- hci
Check it on the machine
grep -wE 'CONFIG_NFC|CONFIG_NFC_HCI' /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 hciPrints 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/arm64, arm64/cloud-arm64, arm64/rt/arm64, armhf/armmp, armhf/armmp-lpae, armhf/rt/armmp, ppc64el/powerpc64le
- trixieMnot built on amd64/cloud-amd64, arm64/arm64, arm64/arm64-16k, arm64/cloud-arm64, arm64/rt/arm64, armel/rpi, armhf/armmp, armhf/armmp-lpae, armhf/rt/armmp, ppc64el/powerpc64le, ppc64el/powerpc64le-64k, riscv64/riscv64, s390x/s390x
- forky, sidMnot built on amd64/cloud-amd64, arm64/arm64, arm64/arm64-16k, arm64/cloud-arm64, arm64/rt-arm64, armhf/armmp, armhf/armmp-lpae, loong64/loong64, ppc64el/powerpc64le, ppc64el/powerpc64le-64k, riscv64/riscv64, s390x/s390x
- M
- a module where it is built at all; some flavours do not build it
- Build switches
- CONFIG_NFC, CONFIG_NFC_HCI
- 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 27.6% of all CVEssource
- CISA KEV
- not listedthe KEV catalogue
- Debian urgency
- not yet assignedsource
- Subsystem
- net/nfc
Upstream fixes
The versions the CNA records as introducing and fixing this, and the commit for each. source
| Introduced | Fixed in | Commit |
|---|---|---|
| 3.5 | 5.10.259 | ed6d5d97dad0 |
| 3.5 | 5.15.210 | b99366d74b53 |
| 3.5 | 6.1.176 | 37382293f174 |
| 3.5 | 6.6.143 | c4cc6b3b0013 |
| 3.5 | 6.12.93 | 1905f5ec3641 |
| 3.5 | 6.18.35 | 22d41b176b99 |
| 3.5 | 7.0.12 | 83b1362edc9d |
| 3.5 | 7.1 | f040e590c035 |
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 triggered by malformed HCP frames from a malicious NFC peer over the RF link; NFC is a proximity wireless medium analogous to Bluetooth, requiring the attacker to be within NFC range (~4 cm) of the victim device.
- AC:LAttack complexity, low
- An attacker with commodity NFC hardware can reliably send a 0-byte HCP frame (or fragment sequence) to trigger the out-of-bounds read and the msg_len integer underflow that leads to skb_over_panic(), with no race or special memory layout required.
- PR:NPrivileges required, none
- Exploitation requires no privileges on the victim system; inbound frames are processed in kernel driver/workqueue context with no authentication, and the attacker only needs an active NFC RF session with the victim's controller.
- UI:NUser interaction, none
- On typical NFC-enabled deployments (Android phones, payment terminals, transit readers), the victim does not need to perform a deliberate administrative action beyond having NFC radio active while an attacker initiates proximity communication.
- S:UScope, unchanged
- Impact is confined to kernel memory and availability on the victim host; it does not cross a VM, container, or IOMMU security boundary.
- C:HConfidentiality impact, high
- The vulnerable code dereferences packet->header from skb->data on a zero-length skb, causing an out-of-bounds heap read of at least one byte of adjacent kernel memory.
- I:HIntegrity impact, high
- The fragment-reassembly path underflows msg_len when processing zero-length fragments, passing a wrapped length to skb_put_data() and attempting a massive kernel buffer write before panic; combined with the heap out-of-bounds read, this is kernel memory corruption with potential for further exploitation.
- A:HAvailability impact, high
- The integer underflow in HCP fragment reassembly reliably triggers skb_over_panic() (kernel BUG/panic), causing complete loss of kernel availability on affected systems.