CVE-2026-97906 bootconfig: Fix integer overflow in initrd size check

What is CVE-2026-97906?

CVE-2026-97906 is a vulnerability in Linux, published on 25 Sep 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:

bootconfig: Fix integer overflow in initrd size check

Sashiko reported that in get_boot_config_from_initrd(), a crafted initrd with a huge bootconfig size (such as 0xFFFFFFFF) can cause the pointer arithmetic:

data = ((void *)hdr) - size;

to wrap around on 32-bit systems (or when pointer subtraction overflows). Because data wraps around, the subsequent bounds check:

if ((unsigned long)data < initrd_start)

evaluates to false, bypassing the check. The kernel then calls xbc_calc_checksum(data, size), which attempts to read 4GB of memory, hitting unmapped pages and triggering a fatal kernel page fault during early boot. Furthermore, on 64-bit systems with an initrd > 4.29 GB, an unbounded 32-bit size can similarly bypass the initrd_start check.

Fix this by: 1. Ensuring the initrd is at least large enough to contain the bootconfig footer and verifying hdr is within the initrd bounds. 2. Checking that size does not exceed XBC_DATA_MAX and does not exceed the available space between initrd_start and hdr before performing pointer subtraction.

Which versions are affected by CVE-2026-97906?

How do I fix CVE-2026-97906?

Apply the vendor's patch.

Is CVE-2026-97906 being exploited?

There is no known exploitation of CVE-2026-97906 in the wild and no public exploit code.

Sources

• CVE record
• NVD
• OSV
• GitHub advisory
• How this page is made

Also known as AZL-104358, BELL-CVE-2026-97906, DEBIAN-CVE-2026-97906, GHSA-rh89-37w4-pmjq, UBUNTU-CVE-2026-97906.