dbcve.org
Pdf EditorApplication · Foxit

CVE-2021-34956

HIGH · 7.8 CVSS v3.0 Published 2024-05-07
Fix available
A fix is available. Upgrade to after 11.0.1.49938 or later.
See remediation →
81/100
Remediation priority · High
No privileges

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 · unedited
Foxit PDF Editor Underline Annotation Use-After-Free Remote Code Execution Vulnerability. This vulnerability allows remote attackers to execute arbitrary code on affected installations of Foxit PDF Editor. 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-14357.

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 confidence

This is a Use-After-Free (UAF) vulnerability in Foxit PDF Editor's handling of Underline Annotations. The vulnerability exists because the code fails to validate the existence of an object before performing operations on it, allowing an attacker to access freed memory and execute arbitrary code in the context of the current process. Exploitation requires user interaction via a malicious PDF file or webpage.

MitigationUpdate Foxit PDF Editor to the latest version to obtain the vendor patch. Until then, avoid opening untrusted PDF files or visiting untrusted websites that could deliver malicious PDF content.

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
Pdf EditorApplication
Affected:<= 10.1.5.37672= 11.0.0.49893= 11.0.1.49938
Pdf ReaderApplication
Affected:<= 11.0.1.49938

CVSS 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 checks

Work through these to decide whether this CVE applies to you.

  1. Check if Foxit PDF software is installed
    Open Windows Settings > Apps > Apps & Features, or check the following registry key: HKLM\SOFTWARE\Microsoft\Windows\CurrentVersion\Uninstall\* for entries containing 'Foxit'. Also check common install paths: C:\Program Files\Foxit Software\ or C:\Program Files (x86)\Foxit Software\
    Affected if No Foxit PDF Editor or Reader is found on the system, the system is not affected by this specific vulnerability
  2. Identify the installed Foxit product type
    In the registry or install folder identified in step 1, determine whether the product is Foxit PDF Editor or Foxit PDF Reader. Check the DisplayName in the registry uninstall entry or the executable name in the installation folder (FoxitPDFEditor.exe vs FoxitPDFReader.exe)
    Affected if The product is neither Foxit PDF Editor nor Foxit PDF Reader
  3. Determine the exact installed version
    Right-click the Foxit executable (FoxitPDFEditor.exe or FoxitPDFReader.exe) in the installation folder, select Properties, then view the Details tab for Product Version. Alternatively, open the Foxit application, go to Help > About to display the version number
    Affected if Unable to determine the version number for comparison
  4. Compare version against affected ranges
    For Foxit PDF Editor: compare your version against <= 10.1.5.37672, = 11.0.0.49893, or = 11.0.1.49938. For Foxit PDF Reader: compare against <= 11.0.1.49938. Note that versions 10.1.5.37673 through 10.1.x and 11.0.0.x (except exact 11.0.0.49893) may not be affected
    Affected if The installed version exactly matches one of the affected version numbers or falls within the <= ranges specified (Editor: 10.1.5.37672 or lower; Reader: 11.0.1.49938 or lower)
  5. Verify Underline annotation capability is present
    Open any PDF in the Foxit application, right-click and look for annotation tools. Underline annotation is a standard feature in Foxit PDF products and cannot be disabled. This check confirms the vulnerable feature exists in the installed product
    Affected if The Underline annotation option is available in the context menu or annotation toolbar

The system is affected if Foxit PDF Editor (version 10.1.5.37672 or lower, or exactly 11.0.0.49893 or 11.0.1.49938) or Foxit PDF Reader (version 11.0.1.49938 or lower) is installed and the Underline annotation feature is accessible.

Generated from the published advisory. Verify against your own configuration.

Check your environment

Paste your version and any relevant configuration and it will be compared against the affected criteria above. Do not include secrets or credentials.

AI-assisted, checked against the advisory. Informational, not a guarantee.

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 data
Upgrade available Upgrade to a release after 11.0.1.49938
Interim mitigation

Update Foxit PDF Editor to the latest version to obtain the vendor patch. Until then, avoid opening untrusted PDF files or visiting untrusted websites that could deliver malicious PDF content.

Fix this in Pdf Editor Scoped from the published advisory
  • Consultation1.0 h
  • Implementation1.0 h
  • Testing1.0 h
  • Review / QA1.0 h
4.0 hours of engineering $750
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Scan for this in your stack

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References Go to the primary sourcePrimary sources — vendor advisories, patches and trackers. Where our summary and a reference disagree, the reference wins.

Primary sources

Practitioner notes

Contributed

Peer-ranked notes from engineers who’ve handled CVE-2021-34956 in production — separate from our analysis above.

No notes yet

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What this is

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.

What belongs here
  • 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
  • No spam, self-promotion, credentials, or personal data