Look up another CVE · open CVE-2026-64151 in the interactive tracker
CVE-2026-64151
iommupt: Check for missing PAGE_SIZE in the pgsize_bitmap
Published 2026-07-19 (3 months ago) by the Linux kernel CNA. Subsystem drivers/iommu. Debian urgency: unimportant.
What to do, per Debian release
Debian's own status for CVE-2026-64151 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 | not affected | 6.12.113-1 | Nothing to do. trixie never shipped the vulnerable code. |
| Debian 14forky | fixed | 7.0.12-1 | Update the kernel and reboot. Fixed in 7.0.12-1. A running kernel keeps the old code until the machine restarts. |
| Debian unstablesid | fixed | 7.0.12-1 | Update the kernel and reboot. Fixed in 7.0.12-1. A running kernel keeps the old code until the machine restarts. |
The vulnerability
What the bug is
Sashiko pointed out that the driver could drop PAGE_SIZE from the pgsize_bitmap. That is technically allowed but nothing does it, and such an iommu_domain would not be used with the DMA API today. Still, it is against the design and it is trivial to fix up. Lift the PT_WARN_ON to the if branch and just skip the fast path.
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/iommu/generic_pt/iommu_pt.h
- What this is
- IOMMU SUBSYSTEMMAINTAINERS section matched on drivers/iommu/ · iommu@lists.linux.dev · Maintained
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?
- ?
- 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
- 2026-07-19 (3 months ago)source
- CVSS
- 8.4 high
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:Nsource recompute it - Attack vector
- local (AV:L)source
- EPSS
- 0.16%, higher than 5.1% of all CVEssource
- CISA KEV
- not listedthe KEV catalogue
- Debian urgency
- unimportantsource
- Subsystem
- drivers/iommu
Upstream fixes
The versions the CNA records as introducing and fixing this, and the commit for each. source
| Introduced | Fixed in | Commit |
|---|---|---|
| 6.19 | 7.0.11 | 00850f41da24 |
| 6.19 | 7.1 | 8ef3f77c4400 |
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 bug is in `map_range()` inside the generic IOMMU page-table path, reached only via local kernel interfaces (`iommu_map()` → `iommu_map_nosync()` → `pt->ops->map_range()`), primarily through `/dev/iommufd` or `/dev/vfio/*` ioctls during device passthrough mapping setup. There is no network-facing entry point.
- AC:LAttack complexity, low
- Once an IOMMU paging domain exists with `PAGE_SIZE` cleared from `pgsize_bitmap`, any `iommu_map()`/`IOMMU_IOAS_MAP` call mapping a single page reliably takes the buggy fast path; the attacker controls mapping requests and needs no races or special memory layout.
- PR:LPrivileges required, low
- Exploitation requires local ability to create IOMMU mappings for a passthrough device (IOMMUFD/VFIO ioctl access and device group permissions), which is available to unprivileged tenants on cloud GPU/NIC passthrough hosts without host root, even though opening `/dev/iommufd` alone is insufficient.
- UI:NUser interaction, none
- Triggering the flaw is entirely programmatic through IOMMU mapping ioctls; no victim interaction such as mounting a filesystem or opening a file is required.
- S:CScope, changed
- Incorrect leaf PTE installation on an IOMMU domain can break DMA isolation, allowing a device to read/write host physical memory outside its authorized mappings—an IOMMU/DMA security-boundary bypass per kernel CVSS guidance.
- C:HConfidentiality impact, high
- Malformed or policy-violating IOMMU page-table entries can cause a DMA-capable device to read arbitrary host physical memory beyond the intended IOVA window, constituting arbitrary memory disclosure through the IOMMU bypass primitive.
- I:HIntegrity impact, high
- The fast path installs `PAGE_SHIFT` leaf entries even when `PAGE_SIZE` is excluded from `pgsize_bitmap`, corrupting IOMMU translation state and enabling a DMA device to write to unauthorized host physical pages.
- A:NAvailability impact, none
- The flaw corrupts IOMMU translation entries rather than causing a kernel oops, panic, or hang; availability impact is not a primary or reliable outcome of triggering this bug.