CVE-2021-27852

CRITICALNVD 9.89.8—Trending — 4 sources updated this weekExploited in the wild

9.8

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.

CVSS v3: 9.8
EG Score: 9.8(high)
EPSS: 96.3%
KEV: ⚠ Exploited

Published

May 27, 2021

Last Modified

October 24, 2025

Advisory Details (2)

Auto-updated Jun 1, 2026

⚠️ Active exploitation confirmed. Patch available. Sources: cert, cisa.

cisa Patch Available🔴 Active Exploitation

Known Exploited Vulnerabilities Catalog | CISA

Known Exploited Vulnerabilities Catalog | CISA. Listed in CISA Known Exploited Vulnerabilities catalog.

https://www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2021-27852

cert🔴 Active Exploitation

VU#706695 - Checkbox Survey insecurely deserializes ASP.NET View State data

https://www.kb.cert.org/vuls/id/706695

Weakness Classification(1)

MITRE Common Weakness Enumeration — the root-cause categories this CVE belongs to.

CWE-502Deserialization of Untrusted Data

Data Freshness Timeline

(refreshed 20× in last 7d / 20× in last 30d)

Every time one of our enrichment pipelines (NVD, MITRE cvelistV5, EPSS, CISA KEV, GHSA, OSV, vendor advisories) ran against this CVE. Most recent first.

2026-06-04 04:38 UTCEG score recompute
2026-06-04 04:38 UTCGHSA enrichment
2026-06-04 00:49 UTCEG score recompute
2026-06-04 00:49 UTCGHSA enrichment
2026-06-03 21:00 UTCEG score recompute
2026-06-03 21:00 UTCGHSA enrichment
2026-06-03 19:09 UTCkev_newly_listed
2026-06-03 17:11 UTCEG score recompute
2026-06-03 17:11 UTCGHSA enrichment
2026-06-03 13:21 UTCEG score recompute
2026-06-03 13:21 UTCGHSA enrichment
2026-06-03 09:32 UTCEG score recompute
2026-06-03 09:32 UTCGHSA enrichment
2026-06-03 05:43 UTCEG score recompute
2026-06-03 05:43 UTCGHSA enrichment
2026-06-03 01:54 UTCEG score recompute
2026-06-03 01:54 UTCGHSA enrichment
2026-06-02 22:05 UTCEG score recompute
2026-06-02 22:05 UTCGHSA enrichment
2026-06-02 20:11 UTCepss_batch

Frequently asked(6)

What is CVE-2021-27852?

CVE-2021-27852 is a critical vulnerability published on May 27, 2021. 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.

When was CVE-2021-27852 disclosed?

CVE-2021-27852 was first published in the National Vulnerability Database on May 27, 2021, with the most recent update on October 24, 2025. EchelonGraph re-ingests CVE updates from NVD on a 2-hour cycle, so this page reflects the latest published state.

Is CVE-2021-27852 actively exploited?

Yes. CISA added CVE-2021-27852 to the Known Exploited Vulnerabilities catalog on April 11, 2022, affecting Checkbox Checkbox Survey. KEV listing indicates confirmed exploitation in the wild; this CVE warrants immediate patching attention.

What is the CVSS score of CVE-2021-27852?

CVE-2021-27852 has a CVSS v3 base score of 9.8 (NVD).

Which products are affected by CVE-2021-27852?

CVE-2021-27852 affects Checkbox Checkbox Survey. The full affected-products list, including version ranges and fixed versions, is shown in the Affected Packages section of this page.

How do I remediate CVE-2021-27852?

Patch to the fixed version published by the affected vendor. Where vendor advisories exist for CVE-2021-27852, EchelonGraph cross-links them in the Vendor Advisories panel below — those typically contain the canonical remediation steps, fixed version numbers, and any vendor-specific mitigations.

Dependency Blast Radius

See which npm, PyPI, Go, and Maven packages are affected by CVE-2021-27852

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Is Your Infrastructure Affected by CVE-2021-27852?

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CVE-2021-27852

📅 Published

🔄 Last Modified

📋 Advisory Details (2)