CVE-2026-53288 arm64: Reserve an extra page for early kernel mapping

Medium 5.5 Published 26 Jun 2026 Updated 26 Jun 2026

A memory corruption vulnerability in the Linux kernel arm64 early mapping allows attackers to cause denial of service or potentially execute code.

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

What is CVE-2026-53288?

CVE-2026-53288 is a medium-severity memory corruption vulnerability in Linux kernel, published on 26 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:

arm64: Reserve an extra page for early kernel mapping

The final part of [data, end) segment may overflow into the next page of init_pg_end[1] which is the gap page before early_init_stack[2]:

[1] crash_arm64_v9.0.1> vtop ffffffed00601000 VIRTUAL PHYSICAL ffffffed00601000 83401000

PAGE DIRECTORY: ffffffecffd62000 PGD: ffffffecffd62da0 => 10000000833fb003 PMD: ffffff80033fb018 => 10000000833fe003 PTE: ffffff80033fe008 => 68000083401f03 PAGE: 83401000

PTE PHYSICAL FLAGS 68000083401f03 83401000 (VALID|SHARED|AF|NG|PXN|UXN)

PAGE PHYSICAL MAPPING INDEX CNT FLAGS fffffffec00d0040 83401000 0 0 1 4000 reserved

[2] ffffffed002c8000 (r) __pi__data ffffffed0054e000 (d) __pi___bss_start ffffffed005f5000 (b) __pi_init_pg_dir ffffffed005fe000 (b) __pi_init_pg_end ffffffed005ff000 (B) early_init_stack ffffffed00608000 (b) __pi__end

For 4K pages, the early kernel mapping may use 2MB block entries but the kernel segments are only 64KB aligned. Segment boundaries that fall within a 2MB block therefore require a PTE table so that different attributes can be applied on either side of the boundary.

KERNEL_SEGMENT_COUNT still correctly counts the five permanent kernel VMAs registered by declare_kernel_vmas(). However, since commit 5973a62efa34 ("arm64: map [_text, _stext) virtual address range non-executable+read-only"), the early mapper also maps [_text, _stext) separately from [_stext, _etext). This adds one more early-only split and can require one more page-table page than the existing EARLY_SEGMENT_EXTRA_PAGES allowance reserves.

Increase the 4K-page early mapping allowance by one page to cover that additional split.

[[email protected]: rewrote part of the commit log] [[email protected]: expanded the code comment]

Weakness: CWE-674

Which versions are affected by CVE-2026-53288?

It affects 1 product.

Products include Linux kernel.

How do I fix CVE-2026-53288?

Apply the vendor's patch.

Upgrade to the fixed version. Memory-safe languages, compiler hardening and fuzzing prevent most new cases. More about Memory corruption.

Is CVE-2026-53288 being exploited?

There is no known exploitation of CVE-2026-53288 in the wild and no public exploit code.

All Linux kernel vulnerabilities

Sources

Also known as BELL-CVE-2026-53288, DEBIAN-CVE-2026-53288, GHSA-24wq-6x4v-q3fv, UBUNTU-CVE-2026-53288.