CVE-2026-71973

Bootloader crash via SquashFS directory allocation overflow

Published Sep 29, 2026 · Updated Sep 29, 2026

Integer overflow in U-Boot's SquashFS parser before 2026.10-rc4 allows attackers to crash the bootloader with a crafted filesystem image. The sqfs_read_directory_table() function multiplies the image-derived metadata-block count by the block size without detecting wraparound, then writes directory data past the undersized heap allocation. Exploitation requires U-Boot to list or load the crafted image; the cited patch discussion establishes a crash, not code execution.

CVSS severityUnavailable
Unscored
EPSS probability0.18%
Next 30 days · Oct 19, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Integer overflow in U-Boot's SquashFS parser before 2026.10-rc4 allows attackers to crash the bootloader with a crafted filesystem image. The sqfs_read_directory_table() function multiplies the image-derived metadata-block count by the block size without detecting wraparound, then writes directory data past the undersized heap allocation. Exploitation requires U-Boot to list or load the crafted image; the cited patch discussion establishes a crash, not code execution.

The record

CVE
CVE-2026-71973
Published
Sep 29, 2026
Updated
Sep 29, 2026
Vendor
DENX Software Engineering GmbH
Product
U-Boot
Classifications
T1499.004
Attack vector
Unavailable
Privileges
Unavailable

Timeline

How it unfolded

  1. Sep 29, 2026CVE publishedPublication date reported by the CVE source.
  2. Sep 29, 2026Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=0 <2026.10-rc4

What conditions does exploitation require?

Attack vectorUnavailable in this record.
Required privilegesUnavailable in this record.

What is affected?

DENX Software Engineering GmbH · U-Bootversion=0 <2026.10-rc4

Published CVSS scores

No CVSS assessment is available in this record.

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

Activity data is delayed. The latest report is Sep 28, 2026.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

No observations available

Sep 22, 2026Sep 28, 2026
Latest reporting daySep 28, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
VectorUnavailable
PrivilegesUnavailable
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

T1499.004Endpoint Denial of Service: Application or System Exploitation

Public exploit references

No public exploit references are available in this record.

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

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Your stack

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