CVE-2021-31476
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 PhantomPDF 10.1.3.37598. 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 XFA templates. The issue results from the lack of proper validation of user-supplied data, which can result in a type confusion condition. An attacker can leverage this vulnerability to execute code in the context of the current process. Was ZDI-CAN-13531.
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 type confusion vulnerability in Foxit PhantomPDF's XFA (XML Forms Architecture) template handling. The lack of proper validation of user-supplied data within XFA templates allows an attacker to trigger type confusion, which can be leveraged to execute arbitrary code in the context of the current process. Exploitation requires user interaction—opening a malicious PDF file or visiting a malicious webpage.
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<= 10.1.3.37598<= 9.7.5.29616>= 10.0.0.0, <= 10.1.3.37598CVSS 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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Identify installed Foxit productOpen the application and go to Help > About, or check Add/Remove Programs (Windows) or the Applications folder (macOS) for Foxit Reader or PhantomPDF installationAffected if Foxit Reader or PhantomPDF is installed
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Determine installed versionIn the About dialog, note the full version number (e.g., 10.1.3.37598). Compare this version against the affected ranges: Reader <= 10.1.3.37598, PhantomPDF <= 9.7.5.29616 or 10.0.0.0 to 10.1.3.37598Affected if Version falls within the affected ranges listed
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Verify XFA functionality is enabledIn the application, go to File > Preferences > Forms. Check if 'Enable XFA' or 'Enable XML Forms Architecture' is checked/enabledAffected if XFA support is enabled (the vulnerability exists in XFA template handling)
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Check JavaScript execution statusGo to File > Preferences > JavaScript. Verify whether JavaScript is enabled or disabled in the applicationAffected if JavaScript execution is enabled (adds attack surface for exploitation)
You are affected if Foxit Reader or PhantomPDF is installed with a version within the affected ranges AND XFA support is enabled, as exploitation requires opening a malicious PDF file that triggers the type confusion in XFA template processing.
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 the vendor security update from Foxit to the latest patched version. As a defense-in-depth measure, disable JavaScript execution in PhantomPDF and avoid opening untrusted PDF files from unknown sources.
- Consultation2.0 h
- Implementation1.0 h
- Testing3.0 h
- Review / QA2.0 h
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Free · runs locallyCheck whether your project pulls in CVE-2021-31476 — 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-2021-31476 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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