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CVE-2026-90025
usb: typec: ucsi: displayport: Fix OOB altmode array index
Published 2026-09-16 (33 days ago) by the Linux kernel CNA. Subsystem drivers/usb. Debian urgency: not yet assigned.
What to do, per Debian release
Debian's own status for CVE-2026-90025 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
The UCSI displayport driver indexes the connector's port altmode array with the GET_CURRENT_CAM response after checking it is not 0xff. The port altmode array is UCSI_MAX_ALTMODES elements long. If the PPM returns an invalid GET_CURRENT_CAM response above UCSI_MAX_ALTMODES and not equal to 0xff, the kernel may crash with an array index OOB error. Update the UCSI displayport driver to verify the current cam is less than UCSI_MAX_ALTMODES before accessing the port altmode array.
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/usb/typec/ucsi/displayport.c
- What this is
- USB TYPEC CLASSMAINTAINERS section matched on drivers/usb/typec/ · linux-usb@vger.kernel.org · Maintained
- Kernel module
- typec_ucsi
Check it on the machine
grep -wE 'CONFIG_OF|CONFIG_PCI|CONFIG_TYPEC|CONFIG_TYPEC_UCSI|CONFIG_USB|CONFIG_USB_GADGET|CONFIG_USB_PHY|CONFIG_USB_SUPPORT' /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 typec_ucsiPrints 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/amd64, amd64/cloud-amd64, amd64/rt/amd64, arm64/cloud-arm64, armhf/armmp, armhf/armmp-lpae, armhf/rt/armmp, i386/686, i386/686-pae, i386/rt/686-pae, ppc64el/powerpc64le
- trixieMnot built on amd64/amd64, amd64/cloud-amd64, amd64/rt/amd64, arm64/cloud-arm64, armel/rpi, ppc64el/powerpc64le, ppc64el/powerpc64le-64k, riscv64/riscv64, s390x/s390x
- forky, sidMnot built on amd64/amd64, amd64/cloud-amd64, amd64/rt-amd64, arm64/cloud-arm64, loong64/loong64, ppc64el/powerpc64le, ppc64el/powerpc64le-64k, riscv64/riscv64, s390x/s390x
- bookworm · linux-6.12Mnot built on amd64/amd64, amd64/cloud-amd64, amd64/rt/amd64, arm64/cloud-arm64, ppc64el/powerpc64le, ppc64el/powerpc64le-64k
- M
- a module where it is built at all; some flavours do not build it
- Build switches
- CONFIG_OF, CONFIG_PCI, CONFIG_TYPEC, CONFIG_TYPEC_UCSI, CONFIG_USB, CONFIG_USB_GADGET, CONFIG_USB_PHY, CONFIG_USB_SUPPORT
- 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
- 2026-09-16 (33 days ago)source
- CVSS
- 7.7 high
CVSS:3.1/AV:L/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:Hsource recompute it - Attack vector
- local (AV:L)source
- EPSS
- 0.17%, higher than 5.9% of all CVEssource
- CISA KEV
- not listedthe KEV catalogue
- Debian urgency
- not yet assignedsource
- Subsystem
- drivers/usb
Upstream fixes
The versions the CNA records as introducing and fixing this, and the commit for each. source
| Introduced | Fixed in | Commit |
|---|---|---|
| 5.2 | 5.10.270 | 8fde7e4a3661 |
| 5.2 | 5.15.221 | 83f1abd62cc1 |
| 5.2 | 6.1.188 | 1ffed96ef986 |
| 5.2 | 6.6.157 | 58e0ee293ec5 |
| 5.2 | 6.12.110 | ac9f878c4680 |
| 5.2 | 6.18.51 | 33a81acd2d1d |
| 5.2 | 7.2.5 | bdaaf3074aed |
| 5.2 | 7.3 | 04cec690b1fd |
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:LAttack vector, local
- The OOB index is the PPM GET_CURRENT_CAM byte from onboard UCSI firmware (ACPI EC, I2C CCG/STM32G0, pmic_glink, Chrome OS EC), not a USB-C partner or network packet. A compromised PPM can report CONNECTED plus DP partner altmodes and drive enter without a physical plug, matching other firmware-to-kernel scores.
- AC:LAttack complexity, low
- The PPM fully controls the GET_CURRENT_CAM u8; any value in 30-254 (UCSI_MAX_ALTMODES is 30, 0xff is the only sentinel) deterministically indexes port_altmode[] out of bounds with no race or attacker-uncontrollable layout.
- PR:NPrivileges required, none
- UCSI connector-change work, GET_CURRENT_CAM, and dp_altmode_probe's automatic enter run in kernel context from PPM notifications with no capable() or credential check, so compromised PPM/EC firmware needs no host account.
- UI:NUser interaction, none
- Partner registration and DisplayPort altmode enter run automatically from PPM connector-change events and dp_altmode_probe scheduled work; no victim must plug a cable, mount media, or open a device node.
- S:UScope, unchanged
- The out-of-bounds pointer load stays inside the host kernel UCSI DisplayPort driver and connector heap; it does not cross a VM, IOMMU, or other security-authority boundary.
- C:HConfidentiality impact, high
- cur is a full u8 used as an index into port_altmode[UCSI_MAX_ALTMODES], so values 30-254 read a kernel pointer from up to about 2KB past the array into adjacent connector/heap memory; that unbounded OOB read scores Confidentiality High.
- I:NIntegrity impact, none
- The OOB pointer is only compared to alt to choose 0 versus -EBUSY; it is never written, stored, or used as a write address, so there is no OOB write, use-after-free, or control-flow hijack primitive.
- A:HAvailability impact, high
- An out-of-range CAM can load from unmapped heap, trip KASAN/UBSAN array-index-out-of-bounds, or oops as the fix describes, producing a kernel panic that the PPM can retrigger on each enter.