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CVE-2026-68253
drm/i915/hdcp: check streams[] bounds before overflow
Published 2026-08-10 (2 months ago) by the Linux kernel CNA. Subsystem drivers/gpu. Debian urgency: not yet assigned.
What to do, per Debian release
Debian's own status for CVE-2026-68253 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-4777-1 · 2026-09-08 · text | 6.1.187-1 | Update the kernel and reboot. DLA-4777-1 shipped the fix on 2026-09-08, in 6.1.187-1. A running kernel keeps the old code until the machine restarts. |
| Debian 13trixie | fixedDSA-6466-1 · 2026-08-25 · text | 6.12.105-1 | Update the kernel and reboot. DSA-6466-1 shipped the fix on 2026-08-25, in 6.12.105-1. A running kernel keeps the old code until the machine restarts. |
| Debian 14forky | fixed | 7.1.6-1 | Update the kernel and reboot. Fixed in 7.1.6-1. A running kernel keeps the old code until the machine restarts. |
| Debian unstablesid | fixed | 7.1.6-1 | Update the kernel and reboot. Fixed in 7.1.6-1. A running kernel keeps the old code until the machine restarts. |
| Debian 12bookworm · linux-6.12 | fixedDLA-4788-1 · 2026-09-19 · text | 6.12.107-1~deb12u1 | Update the kernel and reboot. DLA-4788-1 shipped the fix on 2026-09-19, in 6.12.107-1~deb12u1. A running kernel keeps the old code until the machine restarts. |
The vulnerability
What the bug is
The data->streams[] overflow check is done after the buffer overflow has already happened. Move the overflow check before the write. Side note, emitting a warning splat with a backtrace might be overkill here, but prefer not changing the behaviour other than not doing the overrun. Discovered using AI-assisted static analysis confirmed by Intel Product Security. (cherry picked from commit 9284ab3b6e776c315883ac2611283d263c9460fd)
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/gpu/drm/i915/display/intel_hdcp.c
- What this is
- INTEL DRM DISPLAY FOR XE AND I915 DRIVERSMAINTAINERS section matched on drivers/gpu/drm/i915/display/ · intel-gfx@lists.freedesktop.org · Supported
Show whether Debian builds this, per release
Not established. This site could not find the build rule for the affected file in the kernel trees Debian ships, so it has no answer about whether Debian compiles this code. Read that as unknown, never as absent.
- bookworm, trixie, forky, sid, bookworm · linux-6.12?
- ?
- not established - no Makefile entry for the affected file
Where a release above reads "not established", no build rule for the affected file was found in that release's kernel tree. That is a gap in this lookup, not a finding that the code is absent.
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
Signals
- Published
- 2026-08-10 (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
- 0.14%, higher than 3.2% of all CVEssource
- CISA KEV
- not listedthe KEV catalogue
- Debian urgency
- not yet assignedsource
- Subsystem
- drivers/gpu
Upstream fixes
The versions the CNA records as introducing and fixing this, and the commit for each. source
| Introduced | Fixed in | Commit |
|---|---|---|
| 5.12 | 5.15.217 | 336cf6d80d41 |
| 5.12 | 6.1.184 | 389079bf04e6 |
| 5.12 | 6.6.151 | 84351f123903 |
| 5.12 | 6.12.103 | 2106fb490b2c |
| 5.12 | 6.18.42 | 3d2ef8d38949 |
| 5.12 | 7.1.6 | 984085c5b535 |
| 5.12 | 7.2 | bbb15a6b042d |
Debian advisories
| Advisory | Date | Shipped to | Debian |
|---|---|---|---|
| DLA-4788-1 | 2026-09-19 | bookworm 6.12.107-1~deb12u1 | tracker |
| DLA-4777-1 | 2026-09-08 | bookworm 6.1.187-1 | tracker |
| DSA-6466-1 | 2026-08-25 | trixie 6.12.105-1 | 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 overflow is reached through a local DRM atomic modeset ioctl on /dev/dri/cardN that sets the "Content Protection" connector property, driving intel_hdcp_enable() -> intel_hdcp_prepare_streams(); no network or remote path exists to the i915 display HDCP code.
- AC:LAttack complexity, low
- Any DP MST topology with more connected MST connectors on one digital port than the device has pipes (a common dock/hub/daisy-chain setup, and easily arranged by anyone with access to the machine's display outputs) makes every HDCP enable request overflow the buffer deterministically, with no race or memory-layout condition to win.
- PR:LPrivileges required, low
- The attacker only needs access to the DRM device node as DRM master, which an ordinary user in a local graphical session (video/render group, logind seat) has; no CAP_SYS_ADMIN or root is required to request HDCP content protection on an MST connector.
- UI:NUser interaction, none
- The attacker performs the atomic commit that requests content protection themselves; no action by another user is needed, and on a system already running a compositor with HDCP desired the overflow occurs automatically on the modeset.
- S:UScope, unchanged
- The corruption is confined to kernel heap memory within the same kernel security authority; no VM, IOMMU, or sandbox boundary is crossed.
- C:HConfidentiality impact, high
- The out-of-bounds write corrupts adjacent objects in a small kmalloc slab, and such heap corruption is a standard primitive for pivoting to arbitrary kernel memory disclosure by overwriting neighbouring pointers or length fields.
- I:HIntegrity impact, high
- This is a heap out-of-bounds write past a kzalloc'd streams[] buffer sized to INTEL_NUM_PIPES, with attacker-influenced VCPI values and an attacker-controlled overflow length determined by the MST topology, giving corruption of adjacent slab objects that can be leveraged for control-flow hijack.
- A:HAvailability impact, high
- Overwriting adjacent slab allocations reliably produces slab corruption, oops, or panic, and the path can be re-triggered on every HDCP enable/modeset, so the system can be crashed repeatedly.