CVE-2025-70099
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 · uneditedA NULL pointer dereference in the ext4_dir_en_get_name_len function in include/ext4_dir.h of lwext4 1.0.0 allows attackers to cause a denial of service by supplying a specially crafted EXT4 filesystem image with malformed directory entries. During directory iteration, the code may fail to validate the directory entry pointer before accessing the name_len field, resulting in a segmentation fault. This affects versions based on (or equivalent to) the 2016-era codebase (1.0.0).
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 confidenceA NULL pointer dereference in ext4_dir_en_get_name_len in lwext4 1.0.0 occurs when iterating directories in a specially crafted EXT4 filesystem image. The function fails to validate the directory entry pointer before accessing the name_len field, causing a segmentation fault and denial of service.
Verify against the referenced sources before acting — the references below are authoritative for this CVE, this summary is not.
CVSS 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
- Network
- Complexity
- Low
- Privileges
- None
- User interaction
- None
- Scope
- Unchanged
- Confidentiality
- None
- Integrity
- None
- Availability
- High
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/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 lwext4 library usageSearch for lwext4 library files in your system or dependencies (e.g., liblwext4, lwext4.o, or lwext4 referenced in build files). Check any third-party code that may embed or link to lwext4.Affected if lwext4 version 1.0.0 is present in your environment
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Determine lwext4 versionIf lwext4 is found, check its version string or version header file. Common locations include version.h, README, or the library binary metadata.Affected if the installed version is exactly 1.0.0 (no patches applied)
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Verify EXT4 image processingIdentify processes or code paths that call ext4_dir_en_get_name_len or similar directory entry parsing functions from lwext4. Look for code that mounts, reads, or parses EXT4 filesystem images using this library.Affected if your application or system uses lwext4 to process EXT4 filesystem images
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Check for untrusted image handlingReview whether your system accepts EXT4 filesystem images from untrusted sources (e.g., user uploads, network inputs, removable media). Examine the data flow from image input to lwext4 processing.Affected if EXT4 images from untrusted or external sources are processed by the vulnerable code
Your environment is affected if you run lwext4 version 1.0.0 and process EXT4 filesystem images, especially from untrusted sources, through the ext4_dir_en_get_name_len function.
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 dataValidate directory entry pointers for NULL before dereferencing in ext4_dir_en_get_name_len; avoid mounting untrusted EXT4 filesystem images until patched.
- Consultation3.0 h
- Implementation2.0 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-2025-70099 — 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-2025-70099 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
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