# CVE-2021-23758: Deserialization of Untrusted Data

> CVE-2021-23758: Deserialization of Untrusted Data. CVSS 8.1 (CVSS 3.1), in CISA KEV.

Canonical: https://rewindex.com/cve/CVE-2021-23758
Last updated: 2026-08-27T04:16:38Z

- Published: 2021-12-03 20:05 UTC · Updated: 2026-08-27 04:16 UTC · Assigner: snyk
- CVSS: 8.1 (CVSS 3.1) · Severity: High · Vector: CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H
- EPSS: 82.6%, 100th percentile (scored 2026-10-25)
- CISA KEV: yes, added 2026-08-26, federal due date 2026-09-09, ransomware use: Unknown

## Description

All versions of package ajaxpro.2 are vulnerable to Deserialization of Untrusted Data due to the possibility of deserialization of arbitrary .NET classes, which can be abused to gain remote code execution.

## CISA required action

Apply mitigations in accordance with vendor instructions, ensuring compliance with CISA’s BOD 26-04 Prioritizing Security Updates Based on Risk (see URL in Notes) guidance and CISA’s “Forensics Triage Requirements” (see URL in Notes). Follow applicable BOD 26-04 guidance for cloud services or discontinue use of the product if mitigations are unavailable. Stakeholders are responsible for evaluating each asset's internet exposure and ensuring adherence to BOD 26-04 patching guidelines.

## Affected vendors and products

- n/a: AjaxPro.2

## References

- [CVE record on cve.org](https://www.cve.org/CVERecord?id=CVE-2021-23758)
- [NVD entry](https://nvd.nist.gov/vuln/detail/CVE-2021-23758)
- [http://packetstormsecurity.com/files/175677/AjaxPro-Deserialization-Remote-Code-Execution.html](http://packetstormsecurity.com/files/175677/AjaxPro-Deserialization-Remote-Code-Execution.html)
- [https://github.com/michaelschwarz/Ajax.NET-Professional/commit/b0e63be5f0bb20dfce507cb8a1a9568f6e73de57](https://github.com/michaelschwarz/Ajax.NET-Professional/commit/b0e63be5f0bb20dfce507cb8a1a9568f6e73de57)
- [https://snyk.io/vuln/SNYK-DOTNET-AJAXPRO2-1925971](https://snyk.io/vuln/SNYK-DOTNET-AJAXPRO2-1925971)

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_Sources: CVE records from the CVE Program (cve.org). CVE® is a registered trademark of The MITRE Corporation. (https://www.cve.org/) This product uses data from the NVD API but is not endorsed or certified by the NVD. (https://nvd.nist.gov/) Known Exploited Vulnerabilities catalog from CISA. (https://www.cisa.gov/known-exploited-vulnerabilities-catalog) EPSS scores from FIRST (Exploit Prediction Scoring System). (https://www.first.org/epss/)_


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Canonical: https://rewindex.com/cve/CVE-2021-23758 · Markdown: https://rewindex.com/cve/CVE-2021-23758.md · JSON: https://rewindex.com/api/v1/cves/CVE-2021-23758 · Data licensed CC BY 4.0 (https://creativecommons.org/licenses/by/4.0/) · Generated 2026-10-26T03:12:18.602Z