CVE-2025-70290

Boot-time code execution via undersized ZFS allocation

Published Aug 26, 2026 · Updated Aug 27, 2026

Integer overflow in Denx U-Boot before 2026.04 allows attackers to crash the bootloader or execute code via malformed ZFS metadata. The zfs_nvlist_lookup_nvlist function passes an overflowed metadata-derived size to calloc(), creating an undersized allocation followed by out-of-bounds memory access. Exploitation requires U-Boot's ZFS support to parse attacker-controlled on-disk metadata during boot, placing any code execution in the pre-OS environment.

CVSS severityUnavailable
Unscored
EPSS probability0.46%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Integer overflow in Denx U-Boot before 2026.04 allows attackers to crash the bootloader or execute code via malformed ZFS metadata. The zfs_nvlist_lookup_nvlist function passes an overflowed metadata-derived size to calloc(), creating an undersized allocation followed by out-of-bounds memory access. Exploitation requires U-Boot's ZFS support to parse attacker-controlled on-disk metadata during boot, placing any code execution in the pre-OS environment.

The record

CVE
CVE-2025-70290
Published
Aug 26, 2026
Updated
Aug 27, 2026
Vendor
Unknown vendor
Product
Unknown product
Classifications
Unavailable
Attack vector
Unavailable
Privileges
Unavailable

Timeline

How it unfolded

  1. Aug 26, 2026CVE publishedPublication date reported by the CVE source.
  2. Aug 27, 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?

Affected buildAffected product and version details are unavailable.

What conditions does exploitation require?

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

What is affected?

Affected products and versions are unavailable in this record.

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.

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No observations available

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

Weakness, pattern, technique

No sourced classifications are available.

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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