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CVE-2026-64318
partitions: aix: bound the pp_count scan to the ppe array
Published 2026-07-25 (3 months ago) by the Linux kernel CNA. Subsystem block/partitions. Debian urgency: not yet assigned.
What to do, per Debian release
Debian's own status for CVE-2026-64318 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-4720-1 · 2026-08-05 · text | 6.1.180-1 | Update the kernel and reboot. DLA-4720-1 shipped the fix on 2026-08-05, in 6.1.180-1. A running kernel keeps the old code until the machine restarts. |
| Debian 13trixie | fixed | 6.12.96-1 | Update the kernel and reboot. Fixed in 6.12.96-1. 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-4724-1 · 2026-08-07 · text | 6.12.100-1~deb12u1 | Update the kernel and reboot. DLA-4724-1 shipped the fix on 2026-08-07, in 6.12.100-1~deb12u1. A running kernel keeps the old code until the machine restarts. |
The vulnerability
What the bug is
aix_partition() reads the physical volume descriptor into a fixed-size struct pvd and then scans its physical-partition-extent array: int numpps = be16_to_cpu(pvd->pp_count); ... for (i = 0; i < numpps; i += 1) { struct ppe *p = pvd->ppe + i; ... lp_ix = be16_to_cpu(p->lp_ix); pvd points at a single kmalloc()'d struct pvd whose ppe[] member holds a fixed ARRAY_SIZE(pvd->ppe) (1016) entries, but the loop runs up to the on-disk pp_count. pp_count is an unvalidated __be16 read straight from the descriptor, so a crafted AIX image with pp_count larger than 1016 drives the loop to read pvd->ppe[i] past the end of the allocation (up to 65535 entries, ~2 MB out of bounds). The partition scan runs without mounting anything, when a block device with a crafted AIX/IBM partition table appears (an attacker-supplied image attached with losetup -P, or a device auto-scanned by udev), via msdos_partition() -> aix_partition(). Clamp the scan to the number of entries the ppe[] array can hold.
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.
block/partitions/aix.c
- What this is
- BLOCK LAYERMAINTAINERS section matched on block/ · linux-block@vger.kernel.org · Maintained
Check it on the machine
grep -w CONFIG_AIX_PARTITION /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 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.
- bookwormYnot built on amd64/amd64, amd64/cloud-amd64, amd64/rt/amd64, arm64/arm64, arm64/cloud-arm64, arm64/rt/arm64, armhf/armmp, armhf/armmp-lpae, armhf/rt/armmp, i386/686, i386/686-pae, i386/rt/686-pae
- trixieYnot built on amd64/amd64, amd64/cloud-amd64, amd64/rt/amd64, arm64/arm64, arm64/arm64-16k, arm64/cloud-arm64, arm64/rt/arm64, armel/rpi, armhf/armmp, armhf/armmp-lpae, armhf/rt/armmp, riscv64/riscv64, s390x/s390x
- forky, sidYnot built on amd64/amd64, amd64/cloud-amd64, amd64/rt-amd64, arm64/arm64, arm64/arm64-16k, arm64/cloud-arm64, arm64/rt-arm64, armhf/armmp, armhf/armmp-lpae, loong64/loong64, riscv64/riscv64, s390x/s390x
- bookworm · linux-6.12Ynot built on amd64/amd64, amd64/cloud-amd64, amd64/rt/amd64, arm64/arm64, arm64/arm64-16k, arm64/cloud-arm64, arm64/rt/arm64, armhf/armmp, armhf/armmp-lpae, armhf/rt/armmp
- Y
- built in where it is built at all; some flavours do not build it
- Build switch
- CONFIG_AIX_PARTITION
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
- 7.1 high
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:Hsource recompute it - Attack vector
- local (AV:L)source
- EPSS
- 0.16%, higher than 5.3% of all CVEssource
- CISA KEV
- not listedthe KEV catalogue
- Debian urgency
- not yet assignedsource
- Subsystem
- block/partitions
Upstream fixes
The versions the CNA records as introducing and fixing this, and the commit for each. source
| Introduced | Fixed in | Commit |
|---|---|---|
| 3.11 | 5.10.261 | 09861651617b |
| 3.11 | 5.15.212 | 5eacdb196737 |
| 3.11 | 6.1.178 | b5e9c09309e1 |
| 3.11 | 6.6.145 | fd94a779020f |
| 3.11 | 6.12.96 | 4671bb74bba0 |
| 3.11 | 6.18.39 | ce93228e2193 |
| 3.11 | 7.1.4 | 44f37ee92fdc |
| 3.11 | 7.2 | 2dc0bfd2fe35 |
Debian advisories
| Advisory | Date | Shipped to | Debian |
|---|---|---|---|
| DLA-4724-1 | 2026-08-07 | bookworm 6.12.100-1~deb12u1 | tracker |
| DLA-4723-1 | 2026-08-07 | bullseye 6.1.180-1~deb11u1 | tracker |
| DLA-4720-1 | 2026-08-05 | bookworm 6.1.180-1 | tracker |
| DLA-4717-1 | 2026-08-05 | bullseye 5.10.262-1 | 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
- An attacker with local code execution can supply a crafted image through an unprivileged UDisks loop-setup operation with partition scanning enabled. No network protocol directly invokes this parser.
- AC:LAttack complexity, low
- On an affected build, attacker-controlled on-disk fields deterministically reach the oversized scan without a race or memory-layout requirement for triggering the out-of-bounds access.
- PR:LPrivileges required, low
- A basic active desktop user can request loop setup through UDisks under its default policy, while the kernel loop configuration path itself has no capability check. Initial-namespace root is not required in this deployment.
- UI:NUser interaction, none
- The attacker can initiate loop setup and partition scanning directly, without requiring another user to mount or open the image.
- S:UScope, unchanged
- The vulnerable partition parser and the affected kernel memory belong to the same operating-system security authority, with no demonstrated VM, IOMMU, or sandbox boundary crossing.
- C:HConfidentiality impact, high
- The attacker-controlled count can cause 16-bit reads across nearly 2 MiB beyond the approximately 32 KiB allocation, sampling unrelated kernel memory. This is substantially more than a small bounded disclosure.
- I:NIntegrity impact, none
- The faulty accesses are reads; the derived logical-volume index is range-checked, and subsequent writes remain within the allocated lvip and partition-state arrays. No out-of-bounds write or control-flow write primitive is present.
- A:HAvailability impact, high
- The slab out-of-bounds access is KASAN-confirmed and can produce an oops or panic on hardened kernels or when the traversal reaches inaccessible memory. An attacker can repeat partition scans to sustain denial of service.