Look up another CVE · open CVE-2026-89897 in the interactive tracker
CVE-2026-89897
media: cec: Serialize exclusive follower delivery
Published 2026-09-16 (33 days ago) by the Linux kernel CNA. Subsystem drivers/media. Debian urgency: not yet assigned.
What to do, per Debian release
Debian's own status for CVE-2026-89897 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 | fixedDLA-4841-1 · 2026-10-17 · text | 6.1.190-1 | Update the kernel and reboot. DLA-4841-1 shipped the fix on 2026-10-17, in 6.1.190-1. A running kernel keeps the old code until the machine restarts. |
| Debian 13trixie | fixedDSA-6528-1 · 2026-09-29 · text | 6.12.111-1 | Update the kernel and reboot. DSA-6528-1 shipped the fix on 2026-09-29, in 6.12.111-1. A running kernel keeps the old code until the machine restarts. |
| Debian 14forky | fixed | 7.2.6-1 | Update the kernel and reboot. Fixed in 7.2.6-1. A running kernel keeps the old code until the machine restarts. |
| Debian unstablesid | fixed | 7.2.6-1 | Update the kernel and reboot. Fixed in 7.2.6-1. A running kernel keeps the old code until the machine restarts. |
| Debian 12bookworm · linux-6.12 | fixedDLA-4817-1 · 2026-10-04 · text | 6.12.111-1~deb12u1 | Update the kernel and reboot. DLA-4817-1 shipped the fix on 2026-10-04, in 6.12.111-1~deb12u1. A running kernel keeps the old code until the machine restarts. |
The vulnerability
What the bug is
cec_receive_notify() reads the exclusive follower pointer without the adapter lock. Serialize the no-follower check and message delivery against mode changes and release.
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/media/cec/core/cec-adap.c
- What this is
- CEC FRAMEWORKMAINTAINERS section matched on drivers/media/cec/ · linux-media@vger.kernel.org · Supported
- Kernel module
- cec
Check it on the machine
grep -w CONFIG_CEC_CORE /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 cecPrints 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.
- bookworm, trixie, forky, sid, bookworm · linux-6.12Mnot built on arm64/cloud-arm64
- M
- a module where it is built at all; some flavours do not build it
- Build switch
- CONFIG_CEC_CORE
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
- 2026-09-16 (33 days ago)source
- CVSS
- 7.5 high
CVSS:3.1/AV:A/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:Hsource recompute it - Attack vector
- adjacent network (AV:A)source
- EPSS
- 0.31%, higher than 21.9% of all CVEssource
- CISA KEV
- not listedthe KEV catalogue
- Debian urgency
- not yet assignedsource
- Subsystem
- drivers/media
Upstream fixes
The versions the CNA records as introducing and fixing this, and the commit for each. source
| Introduced | Fixed in | Commit |
|---|---|---|
| 4.8 | 5.10.270 | efc829b4b937 |
| 4.8 | 5.15.221 | cac577854826 |
| 4.8 | 6.1.188 | 4b532b271c91 |
| 4.8 | 6.6.157 | 271e57a936dc |
| 4.8 | 6.12.110 | df941e6851da |
| 4.8 | 6.18.51 | 5c62095acc2a |
| 4.8 | 7.2.5 | ae614f487121 |
| 4.8 | 7.3 | 1924d0788caa |
Debian advisories
| Advisory | Date | Shipped to | Debian |
|---|---|---|---|
| DLA-4841-1 | 2026-10-17 | bookworm 6.1.190-1 | tracker |
| DLA-4817-1 | 2026-10-04 | bookworm 6.12.111-1~deb12u1 | tracker |
| DSA-6528-1 | 2026-09-29 | trixie 6.12.111-1 | tracker |
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
- cec_receive_notify() runs from cec_received_msg_ts() on HDMI-CEC frames a peer places on the shared CEC line. HDMI-CEC is a multi-drop bus among TVs, AVRs, streaming sticks, and conference or automotive HDMI sources, matching CAN/Bluetooth adjacent-segment scoring rather than Internet-routable Network.
- AC:HAttack complexity, high
- The use-after-free requires cec_release() to kfree the exclusive-follower cec_fh after the unlocked pointer load in cec_receive_notify(). A CEC peer can flood receive but cannot close that filehandle, so success depends on concurrent local teardown the attacker cannot initiate.
- PR:NPrivileges required, none
- HDMI-CEC has no authentication. Any device on the same CEC bus can emit frames that the adapter delivers into cec_received_msg_ts() with no Linux account, capability, or user-namespace check on the host.
- UI:NUser interaction, none
- Once the adapter is configured and receiving, which is normal for TVs, Android HDMI-CEC, SBCs, and automotive head units that claim a logical address at boot, RX delivery and any concurrent follower close run without a mount, prompt, or other interactive victim step.
- S:UScope, unchanged
- The use-after-free is of the kmalloc'd struct cec_fh inside the host kernel CEC core and does not cross a VM, IOMMU, or other separate security-authority boundary.
- C:HConfidentiality impact, high
- After cec_release() kfree()s the exclusive follower, cec_queue_msg_fh() still locks and walks lists on the dangling cec_fh. That kernel heap use-after-free enables disclosure of reused object contents.
- I:HIntegrity impact, high
- cec_queue_msg_fh() writes the freed filehandle via mutex operations, list_add_tail of a new cec_msg_entry, and wake_up_interruptible, a heap use-after-free write and control-flow hijack primitive.
- A:HAvailability impact, high
- Using a freed cec_fh from the receive path causes a kernel oops or panic even when not fully exploited for code execution, taking down the host.