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CVE-2026-64280
fpga: dfl-afu: validate DMA mapping length in afu_dma_map_region()
Published 2026-07-25 (3 months ago) by the Linux kernel CNA. Subsystem drivers/fpga. Debian urgency: not yet assigned.
Debian does not build this code. The per-release build detail is under "Where it lives" below.
What to do, per Debian release
Debian's own status for CVE-2026-64280 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-6415-1 · 2026-08-06 · text | 6.12.101-1 | Update the kernel and reboot. DSA-6415-1 shipped the fix on 2026-08-06, in 6.12.101-1. A running kernel keeps the old code until the machine restarts. |
| Debian 14forky | fixed | 7.1.4-1 | Update the kernel and reboot. Fixed in 7.1.4-1. A running kernel keeps the old code until the machine restarts. |
| Debian unstablesid | fixed | 7.1.4-1 | Update the kernel and reboot. Fixed in 7.1.4-1. A running kernel keeps the old code until the machine restarts. |
| Debian 12bookworm · linux-6.12 | fixedDLA-4745-1 · 2026-08-18 · text | 6.12.101-1~deb12u1 | Update the kernel and reboot. DLA-4745-1 shipped the fix on 2026-08-18, in 6.12.101-1~deb12u1. A running kernel keeps the old code until the machine restarts. |
The vulnerability
What the bug is
afu_ioctl_dma_map() accepts a 64-bit length from userspace via DFL_FPGA_PORT_DMA_MAP ioctl without an upper bound check. The value is passed to afu_dma_pin_pages() where npages is derived as length >> PAGE_SHIFT and passed to pin_user_pages_fast() which takes int nr_pages, causing implicit truncation if length is very large. Validate map.length at the ioctl entry point before calling afu_dma_map_region(), rejecting values whose page count exceeds INT_MAX.
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/fpga/dfl-afu-main.c
- What this is
- FPGA DFL DRIVERSMAINTAINERS section matched on drivers/fpga/dfl* · linux-fpga@vger.kernel.org · Maintained
- Kernel module
- none to look for. The file would have gone into dfl_afu, and Debian does not compile it into that module, so finding dfl_afu in lsmod would say nothing about this CVE.
Check it on the machine
grep -wE 'CONFIG_FPGA|CONFIG_FPGA_DFL_AFU' /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.
Show whether Debian builds this, per release
Debian does not build this code. In 5 releases below, every kernel flavour Debian publishes has the switch off, so the vulnerable file is compiled into no kernel binary Debian ships.
- bookworm, trixie, forky, sid, bookworm · linux-6.12n
- n
- not enabled on any flavour - this release does not build the code
- Build switches
- CONFIG_FPGA, CONFIG_FPGA_DFL_AFU
- 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
- 2026-07-25 (3 months ago)source
- CVSS
- 8.8 high
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:C/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/fpga
Upstream fixes
The versions the CNA records as introducing and fixing this, and the commit for each. source
| Introduced | Fixed in | Commit |
|---|---|---|
| 4.19 | 5.10.266 | 5352d488ce4a |
| 4.19 | 5.15.217 | d7e787eee2ea |
| 4.19 | 6.1.184 | a6a3884ff500 |
| 4.19 | 6.6.148 | 16381bda90b2 |
| 4.19 | 6.12.101 | b50e6cd2395c |
| 4.19 | 6.18.39 | 59070040fd12 |
| 4.19 | 7.1.4 | fb2c0eab51ae |
| 4.19 | 7.2 | fc3b071a7c8d |
Debian advisories
| Advisory | Date | Shipped to | Debian |
|---|---|---|---|
| DLA-4777-1 | 2026-09-08 | bookworm 6.1.187-1 | tracker |
| DLA-4745-1 | 2026-08-18 | bookworm 6.12.101-1~deb12u1 | tracker |
| DSA-6415-1 | 2026-08-06 | trixie 6.12.101-1 | 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 vulnerable path is reached locally through DFL_FPGA_PORT_DMA_MAP on a /dev/dfl-port.* character device.
- AC:LAttack complexity, low
- A page-aligned length whose page count wraps to zero or a small positive integer deterministically triggers the mismatch; no race or condition outside the attacker’s control is required.
- PR:LPrivileges required, low
- The ioctl contains no capability or namespace privilege check, so any unprivileged user granted access to the port device can trigger it.
- UI:NUser interaction, none
- The attacker independently opens the device and submits the malicious ioctl without any victim action.
- S:CScope, changed
- The oversized DMA mapping can cross the IOMMU-enforced boundary between the assigned user buffer and host physical memory, affecting kernel and other-user resources.
- C:HConfidentiality impact, high
- A small positive page-count wrap can create an enormous DMA-readable mapping after pinning only a few pages, exposing host memory beyond the authorized buffer; teardown also performs unbounded out-of-bounds pointer reads.
- I:HIntegrity impact, high
- The mapping is DMA_BIDIRECTIONAL, permitting writes beyond the pinned buffer, while the oversized unpin operation can corrupt unrelated page reference counts through out-of-bounds page pointers.
- A:HAvailability impact, high
- A zero page-count wrap causes a deterministic pages[0] dereference from a zero-sized allocation, while other wrapped counts can produce an unbounded unpin traversal and kernel crash.