CVE-2021-34851
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 · uneditedThis vulnerability allows remote attackers to execute arbitrary code on affected installations of Foxit PDF Reader 11.0.0.49893. 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 handling of Annotation objects. The issue results from the lack of validating the existence of an object prior to performing operations on the object. An attacker can leverage this vulnerability to execute code in the context of the current process. Was ZDI-CAN-14016.
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 confidenceThis is a use-after-free or null pointer dereference vulnerability in Foxit PDF Reader 11.0.0.49893 where the software fails to validate the existence of an Annotation object before performing operations on it. An attacker can exploit this by crafting a malicious PDF that, when opened by a user, allows arbitrary code execution in the context of the current 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<= 11.0.0.49893<= 10.1.4.37651= 11.0.0.49893CVSS 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 Foxit PDF Reader versionOpen Foxit PDF Reader, then go to Help > About Foxit Reader to view the version number. Alternatively, right-click the FoxitReader.exe file in the installation directory, select Properties, and check the Details tab for the Product Version.Affected if The version listed is 11.0.0.49893 or any version lower than 11.0.0.49893.
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Check Foxit PDF Editor versionOpen Foxit PDF Editor, then go to Help > About Foxit PDF Editor to view the version number. Alternatively, right-click the PDFEditor.exe file in the installation directory, select Properties, and check the Details tab for the Product Version.Affected if The version listed is 11.0.0.49893, or any version 10.1.4.37651 or lower.
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Confirm vulnerability trigger conditionThis vulnerability requires opening a maliciously crafted PDF file that triggers the software to fail validating the existence of an Annotation object before performing operations on it. Inspect any PDF files received from untrusted sources using the File > Open function in the affected Foxit application.Affected if The software opens and processes PDF files, and the installed version falls within the affected ranges.
A user is affected if they have Foxit PDF Reader version 11.0.0.49893 or lower, or Foxit PDF Editor version 10.1.4.37651 or lower, or exactly version 11.0.0.49893.
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 dataUpdate Foxit PDF Reader to the vendor's patched version. Avoid opening PDF files from untrusted sources until the update is applied.
- Consultation2.0 h
- Implementation2.0 h
- Testing1.0 h
- Review / QA1.0 h
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Free · runs locallyCheck whether your project pulls in CVE-2021-34851 — 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-2021-34851 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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