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CVE-2026-68479
Bluetooth: btrtl: validate firmware patch bounds
Published 2026-08-15 (2 months ago) by the Linux kernel CNA. Subsystem drivers/bluetooth. Debian urgency: not yet assigned.
What to do, per Debian release
Debian's own status for CVE-2026-68479 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 | 6.1.180-1 | Update the kernel and reboot. Fixed in 6.1.180-1. A running kernel keeps the old code until the machine restarts. |
| Debian 13trixie | fixed | 6.12.100-1 | Update the kernel and reboot. Fixed in 6.12.100-1. A running kernel keeps the old code until the machine restarts. |
| Debian 14forky | fixed | 7.1.5-1 | Update the kernel and reboot. Fixed in 7.1.5-1. A running kernel keeps the old code until the machine restarts. |
| Debian unstablesid | fixed | 7.1.5-1 | Update the kernel and reboot. Fixed in 7.1.5-1. A running kernel keeps the old code until the machine restarts. |
The vulnerability
What the bug is
rtlbt_parse_firmware() copies patch_length - 4 bytes before appending the firmware version. A malformed firmware patch shorter than the version field can make this subtraction underflow and turn the copy into an oversized read and write during Bluetooth setup. The existing patch_offset + patch_length check can also wrap on 32-bit architectures. Validate the patch length and range without arithmetic overflow before allocating or copying the patch.
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.
drivers/bluetooth/btrtl.c
- What this is
- BLUETOOTH DRIVERSMAINTAINERS section matched on drivers/bluetooth/ · linux-bluetooth@vger.kernel.org · Supported
- Kernel module
- btrtl
Check it on the machine
grep -wE 'CONFIG_BT|CONFIG_BT_RTL' /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 btrtlPrints 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_RTL
- 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
- 2026-08-15 (2 months ago)source
- CVSS
- 7.8 high
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:Hsource recompute it - Attack vector
- local (AV:L)source
- EPSS
- 0.17%, higher than 5.8% of all CVEssource
- CISA KEV
- not listedthe KEV catalogue
- Debian urgency
- not yet assignedsource
- Subsystem
- drivers/bluetooth
Upstream fixes
The versions the CNA records as introducing and fixing this, and the commit for each. source
| Introduced | Fixed in | Commit |
|---|---|---|
| 4.2 | 5.10.261 | 39e01b4addfb |
| 4.2 | 5.15.212 | bda3c598ade6 |
| 4.2 | 6.1.178 | a4cb830e0b55 |
| 4.2 | 6.6.145 | 68c5a2a19987 |
| 4.2 | 6.12.97 | 83534891c058 |
| 4.2 | 6.18.40 | 6744ab60dfac |
| 4.2 | 7.1.5 | f1ca750c0510 |
| 4.2 | 7.2 | 609c5b04a28d |
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:LAttack vector, local
- Malformed input is parsed from host firmware files via request_firmware() during Realtek Bluetooth hci_power_on/setup (btusb_setup_realtek or h5_btrtl_setup → btrtl_initialize → rtlbt_parse_firmware); no network or Bluetooth packet path reaches this parser.
- AC:LAttack complexity, low
- Attacker fully controls EPATCH patch_length and patch_offset in a crafted firmware blob; unsigned underflow of patch_length-4 and 32-bit patch_offset+patch_length wrap reliably trigger oversized memcpy on the next adapter power-on without races or attacker-uncontrolled layout.
- PR:LPrivileges required, low
- Firmware is loaded from /lib/firmware/rtl_bt/ or Android /vendor/firmware/ paths that on many embedded and phone builds are writable by non-root system or vendor accounts; no init-namespace administrator privileges are needed to position the malicious EPATCH image.
- UI:NUser interaction, none
- rtlbt_parse_firmware runs automatically from hci_dev_setup_sync during hci_power_on when Realtek Bluetooth is enabled at boot or by bluetoothd, requiring no victim interaction such as pairing, mounting, or accepting prompts.
- S:UScope, unchanged
- Heap corruption and out-of-bounds access occur entirely within kernel memory during local firmware parsing on the same host; this does not cross VM, container, or IOMMU security boundaries.
- C:HConfidentiality impact, high
- patch_length-4 unsigned underflow turns memcpy into a massive out-of-bounds read past the kvmemdup firmware buffer, exposing adjacent kernel heap or vmalloc contents well beyond any bounded leak.
- I:HIntegrity impact, high
- The same undersized patch_length allocates a small kvmalloc buffer then memcpy writes a huge amount into kernel heap, yielding a controllable heap overflow and out-of-bounds write usable for privilege escalation.
- A:HAvailability impact, high
- Heap overflow and out-of-range copies during Bluetooth setup commonly cause kernel oops or panic; even without full exploitation the bug produces immediate high availability impact on affected Realtek adapters.