CVE-2021-27852
CriticalExploitedPublic exploitDeserialization of Untrusted Data vulnerability in CheckboxWeb.dll of Checkbox Survey allows an unauthenticated remote attacker to execute arbitrary code.
Published May 27, 2021 · Updated Oct 24, 2025
Key Facts
Patch immediately- CVE-2021-27852 is a critical-severity vulnerability (CVSS 9.8 v3.1) affecting Survey (Checkbox).
- It is exploited in the wild, listed in CISA KEV, Industry KEV feed, CIRCL KEV, ENISA EUVD since Apr 11, 2022. Public exploit code is available.
- EPSS estimates a 30% probability of exploitation in the next 30 days.
- Fixed versions are available, including Survey 7.0, Survey 7.
- Brandefense priority: patch immediately, because it is listed as exploited in the wild.
CVSS v3.1
9.8
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
EPSS (30-day exploit likelihood)
30%
Higher than 98.2% of all scored CVEs
Exploited in the wild
Yes
4 catalog listings
Public exploit code
Available
Proof-of-concept or weaponized module
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Description
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.
Known-Exploited Catalog Listings
| Catalog | Added | Remediation due | Ransomware use |
|---|---|---|---|
| CISA KEV | Apr 11, 2022 | May 2, 2022 | Not reported |
| Industry KEV feed | Apr 11, 2022 | May 2, 2022 | Not reported |
| CIRCL KEV | Apr 11, 2022 | May 2, 2022 | Not reported |
| ENISA EUVD | Apr 11, 2022 | n/a | Not reported |
Required action: Versions 6 and earlier for this product are end-of-life and must be removed from agency networks. Versions 7 and later are not considered vulnerable.
Affected Products
2 affected entries in total| Product | Affected versions | Fixed in |
|---|---|---|
| SurveyCheckbox | >= unspecified | 7.0 |
Patched Releases
Survey
7.0, 7
Timeline
Publicly disclosed
May 27, 2021
Added to CISA KEV
Apr 11, 2022
Added to Industry KEV feed
Apr 11, 2022
Added to CIRCL KEV
Apr 11, 2022
Added to ENISA EUVD
Apr 11, 2022
Last updated
Oct 24, 2025
Weakness Type
- CWE-502 Deserialization of Untrusted Data
References
- advisoryhttps://www.kb.cert.org/vuls/id/706695
- exploitVulnCheck exploitation report
- exploitVulnCheck exploitation report
- exploitVulnCheck exploitation report
- exploitVulnCheck exploitation report
FAQ
Common Questions.
Deserialization of Untrusted Data vulnerability in CheckboxWeb.dll of Checkbox Survey allows an unauthenticated remote attacker to execute arbitrary code.
Affected: Survey (Checkbox) versions >= unspecified. The full list is in the CVE brief.
It is exploited in the wild, listed in CISA KEV, Industry KEV feed, CIRCL KEV, ENISA EUVD since Apr 11, 2022.
Yes. It was added on Apr 11, 2022 with a federal remediation due date of May 2, 2022.
Public exploit code is available.
Fixed versions are available, including Survey 7.0, Survey 7.
Brandefense priority: patch immediately, because it is listed as exploited in the wild.
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