CVE-2026-53047

What the bug is

The krealloc() call for cap_info->phys in __efi_capsule_setup_info() uses sizeof(phys_addr_t *) instead of sizeof(phys_addr_t), which might be causing an undersized allocation. The allocation is also inconsistent with the initial array allocation in efi_capsule_open() that allocates one entry with sizeof(phys_addr_t), and the efi_capsule_write() function that stores phys_addr_t values (not pointers) via page_to_phys(). On 64-bit systems where sizeof(phys_addr_t) == sizeof(phys_addr_t *), this goes unnoticed. On 32-bit systems with PAE where phys_addr_t is 64-bit but pointers are 32-bit, this allocates half the required space, which might lead to a heap buffer overflow when storing physical addresses. This is similar to the bug fixed in commit fccfa646ef36 ("efi/capsule-loader: fix incorrect allocation size") which fixed the same issue at the initial allocation site.

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/firmware/efi/capsule-loader.c

What this is

EXTENSIBLE FIRMWARE INTERFACE (EFI)MAINTAINERS section matched on drivers/firmware/efi/ · linux-efi@vger.kernel.org · Maintained

Kernel module

capsule_loader

Check it on the machine

grep -w CONFIG_EFI_CAPSULE_LOADER /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 capsule_loader

Prints 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.

• bookwormBnot built on ppc64el/powerpc64le
• trixieMnot built on armel/rpi, ppc64el/powerpc64le, ppc64el/powerpc64le-64k, s390x/s390x
• forky, sidMnot built on ppc64el/powerpc64le, ppc64el/powerpc64le-64k, s390x/s390x

B

built in on some, a module on others, absent on the rest

M

a module where it is built at all; some flavours do not build it

Build switch

CONFIG_EFI_CAPSULE_LOADER

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

2026-06-24 (4 months ago)source

CVSS

no vector published, unrated

Attack vector

not published

EPSS

0.18%, higher than 6.6% of all CVEssource

CISA KEV

not listedthe KEV catalogue

Debian urgency

not yet assignedsource

Subsystem

drivers/firmware

Upstream fixes

The versions the CNA records as introducing and fixing this, and the commit for each. source

Introduced	Fixed in	Commit
4.15	5.10.258	22022cd88517
4.15	5.15.209	67adde6bfdfd
4.15	6.1.175	608e1f7bc9d1
4.15	6.6.141	8be69e9245f8
4.15	6.12.91	5e185330d902
4.15	6.18.33	e0e6b14995fd
4.15	7.0.10	ab3f7098a3a2
4.15	7.1	48a428215782
4.14.13	0	0

Debian advisories