CVE-2026-34961
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 · uneditedbarebox prior to version 2026.04.0 contains out-of-bounds read vulnerabilities in ext4 extent parsing due to missing validation of the eh_entries field against buffer capacity in fs/ext4/ext4_common.c. Attackers can supply a malicious ext4 filesystem image via USB, SD card, or network boot to trigger heap out-of-bounds reads during boot-time filesystem parsing, potentially redirecting reads to arbitrary disk offsets.
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 confidencebarebox bootloader before 2026.04.0 has an out-of-bounds read vulnerability in the ext4 filesystem parser. The code fails to validate the eh_entries field (extent header entry count) against available buffer capacity before parsing extent data in fs/ext4/ext4_common.c. Attackers can craft a malicious ext4 filesystem image that causes heap out-of-bounds reads during boot, potentially allowing reads from arbitrary disk offsets.
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< 2026.04.0CVSS 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
- Local
- Complexity
- Low
- Privileges
- None
- User interaction
- None
- Scope
- Unchanged
- Confidentiality
- High
- Integrity
- None
- Availability
- High
CVSS:3.1/AV:L/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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Determine barebox versionRun 'version' command in barebox shell or check boot logs for the barebox version string. Compare against 2026.04.0.Affected if barebox version is earlier than 2026.04.0
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Verify ext4 filesystem support is enabledCheck barebox configuration or run 'ls -l /fs/' to list available filesystem drivers. Look for ext4 or ext4fs entries.Affected if ext4 support is compiled in or loaded as a module
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Identify ext4 mount sourcesReview boot scripts and device tree to identify any ext4 filesystems mounted from USB, SD cards, network mounts, or other removable media.Affected if barebox mounts ext4 filesystems from external or untrusted storage devices
You are affected if your barebox version is earlier than 2026.04.0 AND ext4 filesystem support is enabled AND you mount ext4 filesystems from external sources.
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.
dbcve · scoped2026.04.0
Upgrade barebox to version 2026.04.0 or later which contains the bounds checking fix. Avoid booting from untrusted or unverified ext4 filesystem images via USB, SD cards, or network boot until patched.
2026.04.0
- Identify the current barebox version installed on the target device
- Obtain barebox version 2026.04.0 or later from the official barebox repository (github.com/barebox/barebox)
- Verify the integrity of the downloaded image using checksums provided by the project
- Follow the device-specific flashing procedure to update barebox (typically via USB, SD card, or network boot using the device's boot loader)
- Reboot the device and verify the new barebox version loads successfully
- Test that ext4 filesystem parsing works correctly with the updated version
Generated from the published advisory — verify against the referenced sources before acting.
- Consultation2.0 h
- Implementation4.0 h
- Testing6.0 h
- Review / QA2.0 h
An estimate, not a bill — we confirm scope with you before any work starts. Need it this week? Rush from $3,808.
Scan for this in your stack
Free · runs locallyCheck whether your project pulls in CVE-2026-34961 — 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-2026-34961 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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