CVE-2021-27852
Checkbox Survey Deserialization of Untrusted Data Vulnerability
Checkbox Survey
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.
Exploitation status
CISA Known Exploited Vulnerabilities
Listed by CISA on 11 April 2022. US federal agencies were required to remediate it by 2 May 2022.
EPSS — exploitation probability
FIRST puts the probability of exploitation activity in the next 30 days at 30.3%, which is higher than 98.2% of all scored vulnerabilities. EPSS is a forecast of activity, not a measure of severity, and it is rescored daily.
CVSS vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
Frequently asked questions
Is CVE-2021-27852 being exploited by ransomware groups?
No ransomware group in this database is currently recorded as exploiting CVE-2021-27852.
What does CVE-2021-27852 affect?
CVE-2021-27852 affects Checkbox Survey. 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.
How severe is CVE-2021-27852?
CVE-2021-27852 is rated CRITICAL with a CVSS base score of 9.8. EPSS puts the probability of exploitation in the next 30 days at 30.3%, higher than 98.2% of all scored vulnerabilities. It is listed in the CISA Known Exploited Vulnerabilities catalog, with a federal remediation deadline of 2 May 2022.
How should organisations respond to CVE-2021-27852?
Apply the vendor patch for Checkbox Survey as the first priority, and treat any internet-facing instance as the most urgent. Because this vulnerability is associated with ransomware activity, also review whether the affected systems were reachable before patching, rather than assuming that patching alone closes the incident.