CVE-2021-25801
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 buffer overflow vulnerability in the __Parse_indx component of VideoLAN VLC Media Player 3.0.11 allows attackers to cause an out-of-bounds read via a crafted .avi file.
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 · moderate confidenceA buffer overflow vulnerability exists in the __Parse_indx component of VLC Media Player 3.0.11 when parsing index chunks in AVI files. A specially crafted .avi file with malformed index data triggers an out-of-bounds read beyond allocated buffer boundaries, potentially allowing attackers to read sensitive memory contents or achieve code execution.
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= 3.0.11CVSS 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
- Required
- Scope
- Unchanged
- Confidentiality
- High
- Integrity
- None
- Availability
- High
CVSS:3.1/AV:L/AC:L/PR:N/UI:R/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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Check if VLC Media Player is installedOn Windows: check C:\Program Files\VideoLAN\VLC\vlc.exe or C:\Program Files (x86)\VideoLAN\VLC\vlc.exe exists. On Linux: run 'which vlc' or 'dpkg -l | grep vlc'. On Mac: check /Applications/VLC.app exists.Affected if VLC Media Player is present on the system
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Identify installed VLC versionRun 'vlc --version' from command line or right-click vlc.exe, select Properties, and check the File Version under Details tab. On Linux: 'vlc --version' or check package version with 'apt list --installed vlc' or equivalent.Affected if Version displayed is exactly 3.0.11
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Verify AVI file handling capabilityConfirm VLC is used or configured to open .avi files. Check file associations (Windows: Default Programs > Set Associations, or inspect vlc.exe --prefer-dvd-tab for file type registrations).Affected if VLC is associated with or commonly used to open .avi files
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Assess AVI file processing exposureReview user behavior or system logs for recent .avi file openings. Check download folders, shared directories, or automated media indexing that may process AVI files with VLC.Affected if User opens, previews, or processes .avi files using VLC Media Player
User is affected if VLC Media Player version 3.0.11 is installed AND they open or process .avi files with VLC.
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 dataAvoid opening untrusted or unverified .avi files in VLC Media Player until a security patch is available. Consider upgrading VLC to the latest version once the vulnerability is patched.
- Consultation4.0 h
- Implementation8.0 h
- Testing6.0 h
- Review / QA4.0 h
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Scan for this in your stack
Free · runs locallyCheck whether your project pulls in CVE-2021-25801 — 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-2021-25801 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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