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Linux KernelOperating system · Linux

CVE-2026-53047

MEDIUM · 5.5 CVSS v3.1 Published 2026-06-24
Fix available
A fix is available. Upgrade to 4.15 / 5.10.258 or later.
See remediation →
57/100
Remediation priority · Elevated
Zero-click Patch available 8 weeks old

Official description Straight from the sourceThe vendor's or NVD's own wording, published unedited. Authoritative, but often terse — it says what broke, rarely what to do.

NVD · unedited
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.

Technical summary Written by usOur analysis, written from the advisory, the CVSS vector and the affected-version data. It adds context the advisory leaves out, and never invents facts that are not in the source.

dbcve analysis · high confidence

In the Linux kernel's EFI capsule-loader, a krealloc() call in __efi_capsule_setup_info() incorrectly uses sizeof(phys_addr_t *) instead of sizeof(phys_addr_t) when reallocating the phys array. On 64-bit systems this goes unnoticed as the sizes match, but on 32-bit PAE systems where phys_addr_t is 64-bit but pointers are 32-bit, this allocates half the required space, potentially causing a heap buffer overflow when storing physical addresses.

MitigationThis is a kernel source code bug requiring a one-line fix: change sizeof(phys_addr_t *) to sizeof(phys_addr_t) in the krealloc call. No workarounds exist; systems running affected 32-bit kernels with PAE should prioritize patching.

Verify against the referenced sources before acting — the references below are authoritative for this CVE, this summary is not.

Affected products & versions What the vendor confirmedThe version ranges the vendor confirmed as vulnerable. If your version sits inside a range here, treat yourself as exposed until you have upgraded.

NVD · CPE data
Linux KernelOperating system
Affected:>= 4.14.13, < 4.15>= 4.15.1, < 5.10.258>= 5.11, < 5.15.209>= 5.16, < 6.1.175>= 6.2, < 6.6.141>= 6.7, < 6.12.91>= 6.13, < 6.18.33>= 6.19, < 7.0.10= 4.15

CVSS breakdown How the score is builtThe industry scoring standard. It rates how the flaw is reached, what it takes to exploit, and what an attacker gains — the score is derived from those, not the other way round.

From the vector
Attack vector
Local
Complexity
Low
Privileges
Low
User interaction
None
Scope
Unchanged
Confidentiality
None
Integrity
None
Availability
High

CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H

Am I affected? How to checkSteps we derive from the advisory and the affected-version data, so you can decide whether this CVE reaches your setup. They are a guide, not a scan — your own configuration is the authority.

dbcve checks

Work through these to decide whether this CVE applies to you.

  1. Check kernel version
    Run `uname -r` to get the running kernel version, then compare it against the affected ranges: >= 4.14.13, < 4.15; >= 4.15.1, < 5.10.258; >= 5.11, < 5.15.209; >= 5.16, < 6.1.175; >= 6.2, < 6.6.141; >= 6.7, < 6.12.91; >= 6.13, < 6.18.33; >= 6.19, < 7.0.10; = 4.15
    Affected if The kernel version falls within any of the affected version ranges listed in the CVE
  2. Determine system architecture and phys_addr_t size
    Run `getconf LONG_BIT` to see if the system is 32-bit, and check if the kernel config has CONFIG_PHYS_ADDR_T_64BIT enabled (look for /boot/config-$(uname -r) or /proc/config.gz)
    Affected if The system is a 32-bit kernel (LONG_BIT returns 32) with 64-bit phys_addr_t (CONFIG_PHYS_ADDR_T_64BIT=y), which is the PAE configuration that triggers the bug
  3. Verify efi capsule loader is enabled
    Check if CONFIG_EFI_CAPSULE_LOADER is set in the kernel config (/boot/config-$(uname -r) or /proc/config.gz), or check if efi_capsule_loader module is loaded via `lsmod | grep efi_capsule`
    Affected if The efi capsule loader is compiled in or loaded as a module, as this is the code path that contains the vulnerable krealloc() call
  4. Inspect the source code for the bug
    Look at the file drivers/firmware/efi/capsule-loader.c in the kernel source, specifically the __efi_capsule_setup_info() function, and find the krealloc() call for cap_info->phys; check if it uses sizeof(phys_addr_t *) instead of sizeof(phys_addr_t)
    Affected if The krealloc() call uses sizeof(phys_addr_t *) which causes allocation of half the required memory on 32-bit PAE systems

A user is affected if they run a vulnerable kernel version on a 32-bit PAE system (32-bit pointers with 64-bit phys_addr_t) and have the EFI capsule loader enabled, where the code contains sizeof(phys_addr_t *) instead of sizeof(phys_addr_t).

Generated from the published advisory. Verify against your own configuration.

Check your environment

Paste your version and any relevant configuration and it will be compared against the affected criteria above. Do not include secrets or credentials.

AI-assisted, checked against the advisory. Informational, not a guarantee.

Remediation Closing itWhat it takes to close this. Where a vendor fix exists we point at it; where none exists we say so plainly, and can build one. Effort estimates are scoped from the advisory, not from your codebase.

dbcve · scoped
Upgrade available Upgrade to 4.15 / 5.10.258 / 5.15.209 or later
Fixed in 4.155.10.2585.15.209
Vendor patch git.kernel.org →
Interim mitigation

This is a kernel source code bug requiring a one-line fix: change sizeof(phys_addr_t *) to sizeof(phys_addr_t) in the krealloc call. No workarounds exist; systems running affected 32-bit kernels with PAE should prioritize patching.

Recommended fix High confidence

Linux kernel 5.10.258, 5.15.209, or 6.1.175 (or later stable releases in those branches)

  1. Identify the current running kernel version using `uname -r`
  2. If running a kernel version affected by this vulnerability (>= 4.14.13, < 4.15; >= 4.15.1, < 5.10.258; >= 5.11, < 5.15.209; >= 5.16, < 6.1.175), plan for an upgrade
  3. Upgrade the Linux kernel to a fixed version: 5.10.258 or later in the 5.10.x branch, 5.15.209 or later in the 5.15.x branch, or 6.1.175 or later in the 6.1.x branch
  4. Reboot the system into the upgraded kernel to apply the fix
  5. Alternatively, if using a distribution kernel, apply the distribution-specific security update that includes this fix
  6. Verify the fix is applied by checking the kernel version and confirming the sizeof(phys_addr_t) correction is present in the source code if building custom kernels
Caveat Kernel upgrades may require system reboot and could introduce compatibility changes with custom drivers or modules; ensure backup and test in non-production environment first

Generated from the published advisory — verify against the referenced sources before acting.

Fix this in Linux Kernel Scoped from the published advisory
  • Consultation1.0 h
  • Implementation1.0 h
  • Testing4.0 h
  • Review / QA2.0 h
8.0 hours of engineering $1,340
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References Go to the primary sourcePrimary sources — vendor advisories, patches and trackers. Where our summary and a reference disagree, the reference wins.

Primary sources

Practitioner notes

Contributed

Peer-ranked notes from engineers who’ve handled CVE-2026-53047 in production — separate from our analysis above.

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What this is

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  • Version or environment caveats, and links to real fixes
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