Debian LinuxOperating system · Debian
CVE-2021-3500
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 flaw was found in djvulibre-3.5.28 and earlier. A Stack overflow in function DJVU::DjVuDocument::get_djvu_file() via crafted djvu file may lead to application crash and other consequences.
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 stack overflow vulnerability exists in djvulibre versions 3.5.28 and earlier in the DJVU::DjVuDocument::get_djvu_file() function. Attackers can trigger the overflow by providing a specially crafted DJVU file, causing application crashes and potentially enabling further exploitation.
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
Debian LinuxOperating system
= 10.0= 11.0<= 3.5.28CVSS 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
- High
- Availability
- High
CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:H/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 djvulibre is installedOn Debian-based systems, run: dpkg -l | grep -i djvulibre or dpkg -l | grep -i djvu. On systems with the binaries directly, check for: ddjvu, djvutoxml, djvutxt, or other djvulibre command-line tools.Affected if No djvulibre packages or binaries are found, meaning the software is not installed.
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Determine the installed djvulibre versionRun: dpkg -l djvulibre (or dpkg -l | grep djvulibre) to see the installed version number. Alternatively, if ddjvu is available, run: ddjvu --version to get version information.Affected if The installed version cannot be determined or the package is not found.
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Compare installed version against affected rangeReview the version from the previous step. The affected versions are: Djvulibre Project Djvulibre <= 3.5.28, and Debian Linux 10.0 and 11.0 packages.Affected if The installed version is 3.5.28 or earlier.
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Determine if untrusted DJVU files are processedIdentify if any application or service on the system uses djvulibre to parse or render DJVU files from untrusted sources. Check for file upload handlers, document conversion services, or user-facing features that accept DJVU files.Affected if The system processes DJVU files from untrusted or external sources using djvulibre.
You are affected if djvulibre version 3.5.28 or earlier is installed AND the system processes DJVU files, particularly from untrusted 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.
From vendor dataUpgrade djvulibre to version 3.5.29 or later to patch the stack overflow vulnerability. Alternatively, implement input validation to reject or sanitize untrusted DJVU files before processing.
Fix this in Debian Linux
Scoped from the published advisory
- Consultation3.0 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 $4,128.
Scan for this in your stack
Free · runs locallyCheck whether your project pulls in CVE-2021-3500 — 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-2021-3500 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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A place for practitioners to share what actually worked: a mitigation you’ve tested, a configuration change, a version- or environment-specific caveat, or a link to a verified patch. The most useful notes rise to the top as peers upvote them, so the signal stays high.
- 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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