CVE-2026-97906
bootconfig: Fix integer overflow in initrd size check
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.
INFO
Published Date :
Sept. 25, 2026, 11:17 a.m.
Last Modified :
Sept. 25, 2026, 11:17 a.m.
Remotely Exploit :
No
Source :
416baaa9-dc9f-4396-8d5f-8c081fb06d67
Solution
- Update the Linux kernel to the latest patched version.
- Ensure initrd is large enough for bootconfig footer.
- Validate bootconfig size against XBC_DATA_MAX.
- Check size against available space before pointer arithmetic.
References to Advisories, Solutions, and Tools
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CVE-2026-97906.
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associated with the following CWEs:
Common Attack Pattern Enumeration and Classification (CAPEC)
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weaknesses.
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Vulnerability history details can be useful for understanding the evolution of a vulnerability, and for identifying the most recent changes that may impact the vulnerability's severity, exploitability, or other characteristics.
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New CVE Received by 416baaa9-dc9f-4396-8d5f-8c081fb06d67
Sep. 25, 2026
Action Type Old Value New Value Added 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. Added Affected New affected value received. <a href="https://github.com/CVEProject/cvelistV5/blob/main/cves/2026/97xxx/CVE-2026-97906.json">CVE-2026-97906</a> Added Reference https://git.kernel.org/stable/c/7812d6dab0698001e50e8c2f901e17da3eb6f429 Added Reference https://git.kernel.org/stable/c/8d4343a411eaa182d323ab5b149496416015f27d Added Reference https://git.kernel.org/stable/c/bff9a1579e2c9b2a59fdf3793becc9d7bf5ff1a6