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CVE-2026-97906

Linux: bootconfig: Fix integer overflow in initrd size check

Linux LinuxOperating systems
Open in ThreatlineRecord JSON
CVSS
NoneNot scored
ExploitationNo known exploitationNot in CISA KEV, which does not prove it is unexploitedCISA KEV
Exploit odds (EPSS)0.21%Chance of exploitation activity in the next 30 days, higher than 10% of CVEs. Scored 23 Oct 2026FIRST EPSS
Fixed in97be05f33f79342ea65d9b99c9ad07a93b8eef5aAlso 4d45bc0f8cdf606d5409b5f64a8a6609f6520c03, 8d4343a411eaa182d323ab5b149496416015f27d and 2 moreCVE List
Published25 Sep 2026Updated 21 Oct 2026CVE List

What fixes it

  • 97be05f33f79342ea65d9b99c9ad07a93b8eef5aLinuxCVE List
  • 4d45bc0f8cdf606d5409b5f64a8a6609f6520c03LinuxCVE List
  • 8d4343a411eaa182d323ab5b149496416015f27dLinuxCVE List
  • 7812d6dab0698001e50e8c2f901e17da3eb6f429LinuxCVE List
  • 5.7LinuxCVE List

A fixed version on one release line is not the upgrade target for every line. Check your exact version and any vendor backports.

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.

  1. 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.

Text from CVE List

Affected versions 14

  • Linuxaffected: de462e5f10718517bacf2f84c8aa2804567ef7df before 97be05f33f79342ea65d9b99c9ad07a93b8eef5aCVE List
  • Linuxaffected: de462e5f10718517bacf2f84c8aa2804567ef7df before 4d45bc0f8cdf606d5409b5f64a8a6609f6520c03CVE List
  • Linuxaffected: de462e5f10718517bacf2f84c8aa2804567ef7df before 8d4343a411eaa182d323ab5b149496416015f27dCVE List
  • Linuxaffected: de462e5f10718517bacf2f84c8aa2804567ef7df before bff9a1579e2c9b2a59fdf3793becc9d7bf5ff1a6CVE List
  • Linuxaffected: de462e5f10718517bacf2f84c8aa2804567ef7df before 7812d6dab0698001e50e8c2f901e17da3eb6f429CVE List
  • Linuxaffected: 32394df25d8e46935b442b429d74b37885c4f092CVE List
  • Linuxaffected: 5.6.14 before 5.7CVE List
  • Linuxaffected: 5.7CVE List
  • Linuxunaffected: all versions before 5.7CVE List
  • Linuxunaffected: 6.6.160 through 6.6.*CVE List
  • Linuxunaffected: 6.12.112 through 6.12.*CVE List
  • Linuxunaffected: 6.18.53 through 6.18.*CVE List
  • Linuxunaffected: 7.2.7 through 7.2.*CVE List
  • Linuxunaffected: 7.3CVE List

References 5