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CVE-2026-80721
Bluetooth: ISO: ensure no dangling hcon references in iso_conn
Published 2026-08-28 (2 months ago) by the Linux kernel CNA. Subsystem net/bluetooth. Debian urgency: unimportant.
What to do, per Debian release
Debian's own status for CVE-2026-80721 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 | not affected | 6.1.190-1 | Nothing to do. bookworm never shipped the vulnerable code. |
| Debian 13trixie | vulnerable | 6.12.113-1 | No fix published anywhere yet, neither in Debian nor upstream for the series trixie tracks. Watch the Debian tracker page for this CVE. Advisories for trixie have historically landed a median of 11 days after publication. |
| Debian 14forky | fixed | 7.1.8-1 | Update the kernel and reboot. Fixed in 7.1.8-1. A running kernel keeps the old code until the machine restarts. |
| Debian unstablesid | fixed | 7.1.8-1 | Update the kernel and reboot. Fixed in 7.1.8-1. A running kernel keeps the old code until the machine restarts. |
The vulnerability
What the bug is
After iso_conn_del(), ISO sockets should not dereference the hcon any more. Currently, clearing iso_conn::hcon relies on iso_conn_del() releasing the last reference to the iso_conn. Simplify this by explicitly clearing conn->hcon in iso_conn_del(), to avoid more complex reasoning on races about who holds the last reference.
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/iso.c
- What this is
- BLUETOOTH SUBSYSTEMMAINTAINERS section matched on net/bluetooth/ · linux-bluetooth@vger.kernel.org · Supported
- Kernel module
- bluetooth
Check it on the machine
grep -wE 'CONFIG_BT|CONFIG_BT_LE' /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 bluetoothPrints 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_LE
- 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
- 2026-08-28 (2 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
- 0.38%, higher than 29.9% of all CVEssource
- CISA KEV
- not listedthe KEV catalogue
- Debian urgency
- unimportantsource
- 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 |
|---|---|---|
| 6.13 | 6.18.44 | e941799c31f6 |
| 6.13 | 7.1.8 | cdce8af9291d |
| 6.13 | 7.2 | aa9f7cb2bd3a |
| 6.11.11 | 0 | 0 |
| 6.12.2 | 0 | 0 |
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 in Bluetooth ISO connection teardown (iso_conn_del/iso_conn_free); reachable when an adjacent peer triggers HCI disconnect/connect-failure events or sends ISO traffic processed by iso_recv, without network or physical USB access.
- AC:LAttack complexity, low
- An adjacent attacker controls both sides of the refcount race by timing remote disconnects and ISO packets against local teardown; no rare layout or victim-specific state beyond an active ISO session is required.
- PR:NPrivileges required, none
- No local privileges are required on the victim; an unauthenticated adjacent Bluetooth peer can trigger iso_disconn_cfm/iso_connect_cfm teardown on phones and desktops with Bluetooth and LE Audio/ISO enabled.
- UI:NUser interaction, none
- Exploitation needs no victim interaction during the attack; once Bluetooth is on and an ISO link exists (e.g., LE Audio), remote disconnect and ISO traffic alone can hit the race.
- S:UScope, unchanged
- The flaw causes kernel heap use-after-free on hci_conn via dangling iso_conn::hcon references; impact stays within kernel memory safety, not a VM escape or cross-authority boundary.
- C:HConfidentiality impact, high
- After hci_conn_del frees hcon, iso_conn still holds conn->hcon; subsequent iso_conn_free or socket paths dereference freed hci_conn memory, a classic UAF read primitive.
- I:HIntegrity impact, high
- Use-after-free on hci_conn enables corrupting connection management fields and hci_conn_drop state; such kernel heap UAF bugs are routinely leveraged for arbitrary write and code execution.
- A:HAvailability impact, high
- Dereferencing freed hci_conn in iso_conn_free or ISO socket teardown reliably causes kernel oops or panic, giving unprivileged adjacent attackers a repeatable denial-of-service.