dbcve.org
Actively exploited in the wild. This CVE is on the CISA Known Exploited Vulnerabilities list — treat remediation as urgent. Federal remediation due by 2 May 2022.
SurveyApplication · Checkbox

CVE-2021-27852

CRITICAL · 9.8 CVSS v3.1 Published 2021-05-27
Fix available
A fix is available. Upgrade to 7.0 or later.
See remediation →
100/100
Remediation priority · Urgent
In the wild Remotely reachable No privileges Zero-click

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
Deserialization of Untrusted Data vulnerability in CheckboxWeb.dll of Checkbox Survey allows an unauthenticated remote attacker to execute arbitrary code. This issue affects: Checkbox Survey versions prior to 7.

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

A deserialization vulnerability exists in CheckboxWeb.dll of Checkbox Survey software versions prior to version 7. The flaw allows unauthenticated remote attackers to deserialize untrusted data, leading to arbitrary code execution on the affected system.

MitigationUpgrade Checkbox Survey to version 7 or later to remediate this vulnerability.

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
SurveyApplication
Affected:< 7.0

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
Network
Complexity
Low
Privileges
None
User interaction
None
Scope
Unchanged
Confidentiality
High
Integrity
High
Availability
High

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/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. Locate Checkbox Survey installation directory
    Search for the Checkbox Survey installation folder, typically found in C:\Program Files\Checkbox Survey or C:\Program Files (x86)\Checkbox Survey on Windows servers. Also check IIS web root directories if hosted as a web application.
    Affected if The Checkbox Survey application directory exists on the server
  2. Identify installed Checkbox Survey version
    Look for a version file or check assembly metadata within the CheckboxWeb.dll file. Right-click CheckboxWeb.dll, select Properties, then go to the Details tab to view the File Version. Alternatively, check any version.txt or readme.txt in the installation directory.
    Affected if The version is listed as below 7.0 or the File Version field shows a version number less than 7.0.0.0
  3. Verify CheckboxWeb.dll is present
    Confirm that the file CheckboxWeb.dll exists in the application bin directory or web application's root folder. This DLL contains the vulnerable deserialization handler.
    Affected if CheckboxWeb.dll exists and is part of the deployed application
  4. Confirm application is exposed to network
    Check if the Checkbox Survey web application is accessible externally or on the internal network. Review IIS bindings or server configuration to determine if the application accepts HTTP/HTTPS requests from untrusted sources.
    Affected if The Checkbox Survey web interface is exposed and reachable via network requests, allowing unauthenticated attackers to send malicious payloads

The environment is affected if Checkbox Survey is installed with CheckboxWeb.dll present and the version is below 7.0, with the web application accessible to network attackers.

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.

dbcve · scoped
Upgrade available Upgrade to 7.0 or later
Fixed in 7.0
Interim mitigation

Upgrade Checkbox Survey to version 7 or later to remediate this vulnerability.

Recommended fix Moderate confidence

Checkbox Survey 7.0

  1. Identify current Checkbox Survey version by checking the application or system information
  2. Create a full backup of the Checkbox Survey database and configuration files
  3. Download Checkbox Survey version 7.0 or later from the official Checkbox vendor
  4. Follow vendor documentation to perform the upgrade installation
  5. After upgrade, verify the application is running the new version
  6. Test that critical survey functionality works correctly post-upgrade
Caveat Not specified in provided reference material; minor functionality changes may exist between major versions

Generated from the published advisory — verify against the referenced sources before acting.

Fix this in Survey Exploited in the wild — priority engagement
  • Consultation4.0 h
  • Implementation4.0 h
  • Testing6.0 h
  • Review / QA2.0 h
16.0 hours of engineering $2,780
Get it fixed fast

An estimate, not a bill — we confirm scope with you before any work starts. Need it this week? Rush from $4,448.

Scan for this in your stack

Free · runs locally
dbcve dependency scanner

Check whether your project pulls in CVE-2021-27852 — or any other known-vulnerable package — straight from your lock files. Free and open source; it runs locally and uploads nothing.

Get it on GitHub Scan in the browser

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-2021-27852 in production — separate from our analysis above.

No notes yet

Be the first to add a field note for this CVE — a mitigation you’ve verified, a version caveat, or a link to a working fix. Sign in above to contribute.

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