CVE-2026-71973

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Integer Overflow in U-Boot Bootloader

Publication date: 2026-09-29

Last updated on: 2026-10-02

Assigner: VulnCheck

Description

U-Boot before 2026.10-rc4 contains an integer overflow vulnerability in sqfs_read_directory_table() function when allocating the directory table buffer. Attackers can supply a crafted SquashFS image with an attacker-controlled superblock metablks_count value that causes heap buffer under-allocation and out-of-bounds writes, corrupting heap memory and crashing the bootloader.

CVSS Scores

EPSS Scores

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Meta Information

Published

2026-09-29

Last Modified

2026-10-02

Generated

2026-10-19

AI Q&A

2026-09-30

EPSS Evaluated

2026-10-18

NVD

CVE-2026-71973

EUVD

EUVD-2026-89431

Affected Vendors & Products

Vendor	Product	Version / Range
denx	uboot	to 2026.10-rc4 (exc)

Helpful Resources

Exploitability

CWE

KEV

CWE ID	Description
CWE-190	The product performs a calculation that can produce an integer overflow or wraparound when the logic assumes that the resulting value will always be larger than the original value. This occurs when an integer value is incremented to a value that is too large to store in the associated representation. When this occurs, the value may become a very small or negative number.

Attack-Flow Graph

Executive Summary

U-Boot before version 2026.10-rc4 has an integer overflow flaw in the sqfs_read_directory_table() function. When processing a SquashFS image, it allocates a buffer for the directory table based on the superblock's metablks_count value. Attackers can craft an image with a large metablks_count value to trigger heap under-allocation, leading to out-of-bounds writes that corrupt heap memory and crash the bootloader.

Detection Guidance

This vulnerability is specific to U-Boot bootloaders and requires examining the SquashFS image handling. Check U-Boot versions before 2026.10-rc4 for potential exposure. Inspect boot logs for crashes during SquashFS image processing or heap corruption errors.

Impact Analysis

This vulnerability could allow attackers to crash the U-Boot bootloader by providing a malicious SquashFS image. This may prevent the system from booting, cause data corruption, or enable further exploitation if the bootloader is compromised.

Compliance Impact

This vulnerability may impact compliance with GDPR and HIPAA by potentially allowing unauthorized access or corruption of bootloader memory during system startup. Heap corruption could lead to boot failures or unexpected behavior, which may violate integrity requirements in these standards.

Mitigation Strategies

Upgrade U-Boot to version 2026.10-rc4 or later. Avoid loading untrusted SquashFS images in bootloader environments. Monitor for boot failures or memory corruption during system startup.

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