1. Cleus
  2. Zero-days
  3. CVE-2021-27852
Exploited in the wildServers & business softwareWork IT

CVE-2021-27852 Checkbox Checkbox Survey: unsafe data loading

In plain words: The program unpacks saved data from outside without checking it is safe. Usually lets an attacker run code on the server.

Confirmed exploited by CISA on · US federal patch deadline May 2, 2022

What to do

  1. Install Checkbox's security update for Checkbox Survey. If no update exists, follow the vendor's workaround or stop using the product until one ships.
  2. Keep a list of every internet-facing server you run so nothing is forgotten.
  3. Patch anything in this catalog first, ahead of normal patch cycles.
  4. Put admin and file-transfer apps behind a VPN or single sign-on instead of the open internet.

Who is affected

Work IT. Aimed mostly at company systems — you are affected through the companies you use, not your own phone.

What's at risk: Mass data theft and ransomware: a single flaw in a file-transfer or email server has exposed thousands of organisations at once.

The details

Official name
Checkbox Survey Deserialization of Untrusted Data Vulnerability
Product
Checkbox Checkbox Survey
CISA description
Deserialization of Untrusted Data vulnerability in CheckboxWeb.dll of Checkbox Survey allows an unauthenticated remote attacker to execute arbitrary code.
Type of flaw
Unsafe data loading (CWE-502)
Confirmed exploited
Apr 11, 2022
US federal patch deadline
May 2, 2022

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Answering about CVE-2021-27852 ·

Questions about CVE-2021-27852

Is CVE-2021-27852 being exploited?

Yes. CISA added CVE-2021-27852 to its Known Exploited Vulnerabilities catalog on Apr 11, 2022, which means there is reliable evidence of real-world attacks.

How do I fix CVE-2021-27852?

Install Checkbox's security update for Checkbox Survey. If no update exists, follow the vendor's workaround or stop using the product until one ships. Keep a list of every internet-facing server you run so nothing is forgotten.

Am I affected by CVE-2021-27852?

Only if you use Checkbox Checkbox Survey. Aimed mostly at company systems — you are affected through the companies you use, not your own phone.

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