CVE-2021-31455
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 Reader 10.1.1.37576. 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 forms. 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-13100.
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 Reader's XFA (XML Forms Architecture) form handling. The vulnerability exists because the software fails to validate the existence of an object before performing operations on it, allowing an attacker to execute arbitrary code in the context of the current process via a maliciously crafted PDF file.
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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Check Foxit Reader versionOpen Foxit Reader, go to Help > About Foxit Reader, or check Add/Remove Programs to find the installed version numberAffected if Version is 10.1.3.37598 or earlier (any version <= 10.1.3.37598)
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Check PhantomPDF version if installedOpen PhantomPDF, go to Help > About PhantomPDF, or check Add/Remove Programs to find the installed version numberAffected if Version is <= 9.7.5.29616 OR >= 10.0.0.0 and <= 10.1.3.37598 (falls within either affected range)
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Verify XFA form support statusIn Foxit Reader or PhantomPDF, go to File > Preferences > Forms. Check if 'Enable XFA forms' or similar XFA-related option is checked/enabledAffected if XFA forms are enabled - the vulnerability requires XFA form handling to be active to be triggered
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Identify PDF files using XFA formsOpen suspected PDF files in a text editor and search for 'xfa' namespace declarations or XFA-related XML structures within the PDFAffected if PDFs contain XFA form data - malicious XFA content would be required to trigger the vulnerability
You are affected if you have Foxit Reader <= 10.1.3.37598 or PhantomPDF in the affected version ranges AND XFA form support is enabled in the application settings.
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 Reader to the latest patched version. Until patched, exercise caution with untrusted PDF files and consider disabling XFA form support in the application settings.
- Consultation3.0 h
- Implementation6.0 h
- Testing3.0 h
- Review / QA2.0 h
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Free · runs locallyCheck whether your project pulls in CVE-2021-31455 — 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-2021-31455 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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- Version or environment caveats, and links to real fixes
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