Threats / Checkbox / CVE-2021-27852
CVE-2021-27852
· EUVD no mirror located
· GCVE no mirror located
Verified 2026-06-22
Checkbox Survey vulnerability
Deserialization of untrusted data in Checkbox Survey allows unauthenticated remote attackers to execute arbitrary code via CheckboxWeb.dll.
Verdict
Today item — known-exploited.
An unauthenticated remote attacker can exploit unsafe deserialization to achieve arbitrary code execution on systems running vulnerable Checkbox Survey instances, with active exploitation observed in the wild.
01
Is it exploitable?
— the evidence, ranked above the scoreReported exploitation
5 independent public reports of in-the-wild exploitation are cataloged.Distinct reporting sources (vendor, incident response, government); open them for the underlying claims.
Exploited in the wild
Listed in the CISA Known Exploited Vulnerabilities catalog (added 2022-04-11).
Probability (EPSS)
EPSS 0.31946 — modeled likelihood of exploitation activity.EPSS is a daily-changing model output — open the source for today's value.
Severity / affected
Affected: Checkbox, Checkbox Survey. Confirm exact fixed builds in the vendor advisory.
Weakness (CWE)
Mapped to CWE-502 Deserialization of Untrusted Data — weakness family: Injection.CWE assignment from the public NVD record; the weakness class drives how the flaw is exploited.
02
Who’s exploiting it?
— attribution turns risk into urgencyAttribution not established
No confirmed (advisory-backed) threat-actor attribution is established for this record. Absence of a named actor is not absence of compromise — see Coverage & confidence.
03
Why it matters
— the attack path, told twice: adversary, then board1
Front door — unauthenticated access narrative 1
Attacker
I craft a malicious serialized object and send it to the vulnerable deserialization endpoint without authentication.
Business
The organization's survey infrastructure becomes a direct entry point for unauthorized code execution without requiring valid credentials.
2
Keys to the kingdom — privilege/identity takeover narrative 2
Attacker
I trigger deserialization of my payload within CheckboxWeb.dll, causing arbitrary code to execute in the application's process context.
Business
Attackers gain the ability to run commands with the privileges of the web application, potentially compromising data and systems.
3
Lateral reach — past segmentation narrative 3
Attacker
I establish persistence or pivot to other systems on the network using the compromised survey application as a foothold.
Business
The breach expands beyond the survey platform to affect connected infrastructure and sensitive business data.
04
What to do
— defensible action- Remediate per the vendor advisory — confirm the fixed build for your version and verify exposure.1
Say it to the boardA vulnerability with this evidence profile is a defensible budget line, not a backlog ticket — fund the change against the proof above.
05