CVE-2024-42040
Official description Straight from the sourceThe vendor's or NVD's own wording, published unedited. Authoritative, but often terse — it says what broke, rarely what to do.
NVD · uneditedBuffer Overflow vulnerability in the net/bootp.c in DENEX U-Boot from its initial commit in 2002 (3861aa5) up to today on any platform allows an attacker on the local network to leak memory from four up to 32 bytes of memory stored behind the packet to the network depending on the later use of DHCP-provided parameters via crafted DHCP responses.
Technical summary Written by usOur analysis, written from the advisory, the CVSS vector and the affected-version data. It adds context the advisory leaves out, and never invents facts that are not in the source.
dbcve analysis · high confidenceBuffer overflow in U-Boot's BOOTP/DHCP packet parser (net/bootp.c) allows a local network attacker to leak 4-32 bytes of heap/stack memory beyond the allocated packet buffer via specially crafted DHCP responses. The vulnerability exists in code dating back to 2002 and affects all platforms using DENEX U-Boot with DHCP/BOOTP enabled.
Verify against the referenced sources before acting — the references below are authoritative for this CVE, this summary is not.
Affected products & versions What the vendor confirmedThe version ranges the vendor confirmed as vulnerable. If your version sits inside a range here, treat yourself as exposed until you have upgraded.
NVD · CPE data<= 2025.10CVSS breakdown How the score is builtThe industry scoring standard. It rates how the flaw is reached, what it takes to exploit, and what an attacker gains — the score is derived from those, not the other way round.
From the vector- Attack vector
- Adjacent
- Complexity
- Low
- Privileges
- None
- User interaction
- None
- Scope
- Unchanged
- Confidentiality
- High
- Integrity
- None
- Availability
- High
CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:H
Am I affected? How to checkSteps we derive from the advisory and the affected-version data, so you can decide whether this CVE reaches your setup. They are a guide, not a scan — your own configuration is the authority.
dbcve checksWork through these to decide whether this CVE applies to you.
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Identify U-Boot implementationRun the U-Boot `version` command or check the bootloader binary strings for 'Denx' or 'U-Boot' identifiersAffected if The system uses anything other than Denx U-Boot (the vulnerability only affects Denx U-Boot)
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Determine U-Boot versionExecute the `version` command in U-Boot console or inspect the version string in the U-Boot binary; compare against the affected range <= 2025.10Affected if The installed version is 2025.10 or earlier, or if the version cannot be determined but Denx U-Boot is in use
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Verify DHCP/BOOTP is enabledCheck the U-Boot configuration file (.config or defconfig) for CONFIG_BOOTP_* or CONFIG_DHCP options, or run `printenv` and look for DHCP-related environment variables like `bootp` or `dhcp`Affected if DHCP or BOOTP functionality is enabled in the U-Boot configuration (the vulnerability only triggers when DHCP/BOOTP is active)
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Confirm network stack is compiledInspect the compiled U-Boot image for the presence of net/bootp.c by checking for strings like 'bootp' or 'DHCP' in the binary, or review build configuration for NET config optionsAffected if The networking stack with BOOTP/DHCP support is compiled into the U-Boot image
A system is affected if it runs Denx U-Boot version 2025.10 or earlier with DHCP/BOOTP networking functionality enabled, as the buffer overflow in the BOOTP packet parser requires both conditions to be exploitable.
Generated from the published advisory. Verify against your own configuration.
Remediation Closing itWhat it takes to close this. Where a vendor fix exists we point at it; where none exists we say so plainly, and can build one. Effort estimates are scoped from the advisory, not from your codebase.
From vendor dataUpdate DENEX U-Boot to the latest version containing the security patch. If patching is not immediately feasible, disable DHCP/BOOTP functionality in U-Boot configuration if not required, or implement network segmentation to restrict DHCP responses to trusted servers only.
- Consultation3.0 h
- Implementation6.0 h
- Testing4.0 h
- Review / QA2.0 h
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Scan for this in your stack
Free · runs locallyCheck whether your project pulls in CVE-2024-42040 — or any other known-vulnerable package — straight from your lock files. Free and open source; it runs locally and uploads nothing.
References Go to the primary sourcePrimary sources — vendor advisories, patches and trackers. Where our summary and a reference disagree, the reference wins.
Primary sourcesPractitioner notes
ContributedPeer-ranked notes from engineers who’ve handled CVE-2024-42040 in production — separate from our analysis above.
The advisory tells you what broke. It rarely tells you what actually worked. If you’ve dealt with this one, that detail is what the next engineer is searching for.
- The version that genuinely resolved it — not the one the vendor claimed
- A config change or rule that shut the vector down
- A gotcha in the upgrade path that cost you an afternoon
No notes yet
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- Verified mitigations, workarounds, and config changes
- Version or environment caveats, and links to real fixes
- No weaponised exploit code, or anything meant to cause harm
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