# CVE-2026-53047: efi/capsule-loader: fix incorrect sizeof in phys array reallocation

> Incorrect memory allocation size in the Linux kernel EFI capsule loader can cause heap buffer overflow on 32-bit PAE systems, potentially allowing code execution.

- **Severity:** Medium 5.5 (`CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H`)
- **Exploited in the wild:** Not known
- **Login needed:** Any signed-in user
- **Attackable:** Local or same network only
- **Victim action needed:** Not needed
- **Fix available:** Yes
- **Published:** 24 Jun 2026
- **Updated:** 24 Jun 2026
- **Also known as:** BELL-CVE-2026-53047, DEBIAN-CVE-2026-53047, GHSA-jp44-vj5f-4fr8, ROOT-OS-DEBIAN-11-CVE-2026-53047, ROOT-OS-DEBIAN-12-CVE-2026-53047, ROOT-OS-UBUNTU-2204-CVE-2026-53047, ROOT-OS-UBUNTU-2404-CVE-2026-53047, UBUNTU-CVE-2026-53047

## What is CVE-2026-53047?

CVE-2026-53047 is a medium-severity memory corruption vulnerability in Linux kernel, published on 24 Jun 2026. It can only be exploited from the same machine or local network, with no action from the victim.

### Official description

In the Linux kernel, the following vulnerability has been resolved:

efi/capsule-loader: fix incorrect sizeof in phys array reallocation

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.

## Which versions are affected by CVE-2026-53047?

It affects 1 product.


Products: Linux kernel.

## How do I fix CVE-2026-53047?

Apply the vendor's patch.

## Is CVE-2026-53047 being exploited?

There is no known exploitation of CVE-2026-53047 in the wild and no public exploit code.

## Other vulnerabilities in Linux kernel

- [CVE-2026-53266](https://insights.sbomify.com/CVE-2026-53266/): Linux Kernel Out-of-Bounds Write (high 8.8, exploited in the wild)
- [CVE-2013-6282](https://insights.sbomify.com/CVE-2013-6282/): Linux Kernel Improper Input Validation (high 8.8, exploited in the wild)
- [CVE-2022-0185](https://insights.sbomify.com/CVE-2022-0185/): Linux Kernel Heap-Based Buffer Overflow (high 8.4, exploited in the wild)
- [CVE-2013-2094](https://insights.sbomify.com/CVE-2013-2094/): Linux Kernel Privilege Escalation (high 8.4, exploited in the wild)
- [CVE-2026-53362](https://insights.sbomify.com/CVE-2026-53362/): Linux Kernel Unspecified (high 7.8, exploited in the wild)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-53047 and fix it if it is affected.

What it is: CVE-2026-53047 is a medium-severity memory corruption vulnerability in Linux kernel, published on 24 Jun 2026. It can only be exploited from the same machine or local network, with no action from the victim.
Exploitation: There is no known exploitation of CVE-2026-53047 in the wild and no public exploit code.

Affected product: Linux kernel. No package-level version data is available, so check the vendor advisory linked from the reference page.

Task:
1. Search the dependency manifests and lockfiles (for example package.json, package-lock.json, requirements.txt, poetry.lock, uv.lock, pom.xml, build.gradle, go.mod, Cargo.lock, Gemfile.lock) and any Dockerfiles for the affected packages, including transitive dependencies.
2. If an affected version is in use, upgrade it to the fixed version for its release line with the project's package manager, so the lockfile is regenerated. Prefer the smallest upgrade that fixes it.
3. If there is no fix, or the upgrade would break the build, do not guess: explain the risk and the safest workaround instead.
4. Run the tests and summarise what changed and why.
5. If nothing in the project is affected, say so and change nothing.

Reference: https://insights.sbomify.com/CVE-2026-53047/ (Markdown: https://insights.sbomify.com/CVE-2026-53047/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-53047
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-53047
- OSV: https://osv.dev/vulnerability/CVE-2026-53047

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-53047/
Summaries are generated and may contain mistakes; the official description above is the record.