CVE-2021-34971
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 · uneditedFoxit PDF Reader JPG2000 File Parsing Heap-based Buffer Overflow Remote Code Execution Vulnerability. This vulnerability allows remote attackers to execute arbitrary code on affected installations of Foxit PDF Reader. User interaction is required to exploit this vulnerability in that the target must visit a malicious page or open a malicious file. The specific flaw exists within the parsing of PDF files. The issue results from the lack of proper validation of the length of user-supplied data prior to copying it to a heap-based buffer. An attacker can leverage this vulnerability to execute code in the context of the current process. Was ZDI-CAN-14812.
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 confidenceHeap-based buffer overflow vulnerability in Foxit PDF Reader's JPG2000 image parsing due to insufficient validation of user-supplied data length before copying into heap memory. An attacker can trigger this by crafting a malicious PDF file, causing memory corruption that leads to arbitrary code execution in the context of the current user process.
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<= 10.1.5.37672= 11.0.0.49893= 11.0.1.49938<= 11.0.1.49938CVSS 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:3.0/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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Identify installed Foxit productOpen Windows Settings > Apps & Features or use Control Panel > Programs and Features. Look for 'Foxit PDF Reader' or 'Foxit PDF Editor' in the installed programs list.Affected if Either Foxit PDF Reader or Foxit PDF Editor is installed on the system
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Determine installed Foxit versionRight-click on the Foxit icon or executable, select Properties, then go to the Details tab to view the 'Product version' field. Alternatively, open Foxit and navigate to Help > About Foxit Reader/Editor to display the version number.Affected if The exact version number cannot be determined from the product
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Compare Reader version against affected rangeIf Foxit PDF Reader is installed, compare its version number to 11.0.1.49938. Versions less than or equal to 11.0.1.49938 are affected.Affected if Foxit PDF Reader version is <= 11.0.1.49938
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Compare Editor version against affected rangesIf Foxit PDF Editor is installed, compare its version to: 10.1.5.37672 (any version <= this is affected), 11.0.0.49893, or 11.0.1.49938.Affected if Foxit PDF Editor version is <= 10.1.5.37672, OR equals 11.0.0.49893, OR equals 11.0.1.49938
The user is affected if Foxit PDF Reader <= 11.0.1.49938 or Foxit PDF Editor in any of the specific affected versions (10.1.5.37672 and below, 11.0.0.49893, or 11.0.1.49938) is installed on the system.
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 dataApply vendor-supplied patches from Foxit to address the vulnerability. Until patched, avoid opening PDF files from untrusted sources and disable automatic JavaScript execution in Foxit Reader.
- Consultation4.0 h
- Implementation8.0 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-2021-34971 — 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-2021-34971 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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