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Advisory severityMedium5.5Red Hat Linux

Medium [CVE-2026-53047] fix incorrect sizeof in phys array reallocation

This medium-severity Red Hat Linux advisory covers CVE-2026-53047 affecting Red Hat Enterprise Linux 9, Red Hat package: kernel-rt.

Aggregated and source-linked by VulniPulse. Data sources, validation and limitations.

CVE-2026-53047 Source published Source updated

VulniPulse record published Record updated

CVE-2026-53047
Affected products & platforms
Red Hat LinuxLinux Kernel
Open source advisory

Summary

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. An incorrect size calculation during memory reallocation for physical addresses can lead to an undersized buffer.

This could potentially allow a local attacker to cause a denial of service or achieve arbitrary code execution. Red Hat severity: Moderate — CVSS 5.5 (CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H).

Weakness: CWE-131.

Is CVE-2026-53047 exploited?

No exploitation is reported in the sources VulniPulse tracks: CVE-2026-53047 is not in the CISA KEV catalog (checked ) and this advisory does not report exploitation. That is not proof the vulnerability cannot be exploited.

How do I fix CVE-2026-53047?

The advisory VulniPulse tracks names no fixed release. Follow Red Hat's guidance for workarounds and updates.

Confirm against the vendor advisory before you patch.

Affected versions

No affected-version range was extracted from the source record. The vendor advisory is authoritative. Check it before change work.

Official advisory · medium-confidence parse· fetched 14 days ago·verify at source

Fixed versions

No fixed release is recorded yet. That does not prove no patch exists. Confirm against the vendor advisory.

Official advisory · medium-confidence parse· fetched 14 days ago·verify at source

Mitigation

The source record does not include mitigation steps. That does not mean no fix exists. Read the vendor advisory below for the authoritative guidance.

Official advisory · medium-confidence parse· fetched 14 days ago·verify at source

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