CVE-2026-34961

Bootloader crash via unchecked ext4 extent count

Published May 11, 2026 · Updated May 11, 2026

Out-of-bounds reads in barebox before 2026.04.0 allow attackers to crash the bootloader through a crafted ext4 filesystem image. The extent walker in fs/ext4/ext4_common.c uses the on-disk eh_entries value as a loop bound without checking the containing buffer's entry capacity. Exploitation requires barebox to mount the crafted image from boot media or a network filesystem, and a resulting fault can halt the boot process.

CVSS severity6.9
Medium
EPSS probability0.21%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Out-of-bounds reads in barebox before 2026.04.0 allow attackers to crash the bootloader through a crafted ext4 filesystem image. The extent walker in fs/ext4/ext4_common.c uses the on-disk eh_entries value as a loop bound without checking the containing buffer's entry capacity. Exploitation requires barebox to mount the crafted image from boot media or a network filesystem, and a resulting fault can halt the boot process.

The record

CVE
CVE-2026-34961
Published
May 11, 2026
Updated
May 11, 2026
Vendor
Pengutronix
Product
barebox
Classifications
CWE-125, T1499
Attack vector
local
Privileges
unauthenticated

Timeline

How it unfolded

  1. May 11, 2026CVE publishedPublication date reported by the CVE source.
  2. May 11, 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 <=2026.04.0

What conditions does exploitation require?

Attack vectorlocal
Required privilegesunauthenticated

What is affected?

Pengutronix · bareboxversion=0 <=2026.04.0

Published CVSS scores

7.7NIST NVDCVSS:3.1/AV:L/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:H
6.2VulnCheckCVSS:3.1/AV:L/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
6.9VulnCheckCVSS:4.0/AV:L/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N

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.

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

No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectorlocal
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-125Out-of-bounds Read
T1499Endpoint Denial of Service

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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