Ajax.NET Professional Deserialization of Untrusted Data Vulnerability

Are you affected?

Enter the version you run. The result uses only the ranges stored on this record.

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• cpe ajaxpro.2 project/ajaxpro.2version unspecified
• cpe michaelschwarz/ajax.net professionalversion unspecified
• vendor Ajax.NET Professional Ajax.NET Professionalversion unspecified

How to fix CVE-2021-23758

• Recommended remediation

  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. CISA due date Sep 9, 2026.

• Official advisories

  • CISA KEV · cisa.gov
  • CVE.org · cve.org
  • FIRST EPSS · first.org
  • NIST NVD · nvd.nist.gov
  • Packet Storm Security · packetstormsecurity.com
  • VulnCheck KEV · vulncheck.com

What to do

Three questions, each answered from this record only. Confirm the vendor advisory before you patch.

Code

The project this record applies to. Exploit listings stay in References.

• Repository · github.com

Timeline

Detection, updates, and resolution for this record.

1. Dec 3, 2021 · Catalog

   Detected

   Ajax.NET Professional (AjaxPro) contains a deserialization of untrusted data vulnerability that could allow for remote code execution via arbitrary .NET classes. The impacted product(s) could be end-of-life (EoL) and/or end-of-service (EoS). Users are advised to discontinue use and/or transition to a supported version.

2. Aug 26, 2026 · CISA KEV

   Known exploited

   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

3. Aug 26, 2026 · Catalog

   Updated

   Ajax.NET Professional (AjaxPro) contains a deserialization of untrusted data vulnerability that could allow for remote code execution via arbitrary .NET classes. The impacted product(s) could be end-of-life (EoL) and/or end-of-service (EoS). Users are advised to discontinue use and/or transition to a supported version.

4. Sep 9, 2026 · CISA KEV

   Remediation due

   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

Sources

• CISA KEVConfirmed exploitationCVE-2021-23758

  Ajax.NET Professional (AjaxPro) contains a deserialization of untrusted data vulnerability that could allow for remote code execution via arbitrary .NET classes. The impacted product(s) could be end-of-life (EoL) and/or end-of-service (EoS). Users are advised to discontinue use and/or transition to a supported version.

  cisa.gov
• CVE.orgVulnerability recordCVE-2021-23758

  Official CVE identifier

  cve.org
• FIRST EPSSExploitation probabilityCVE-2021-23758

  30-day exploitation probability 82.6%

  first.org
• Metasploit ModulesPublic exploit moduleexploit_windows/http/ajaxpro_deserialization_rce

  Public module reference (excellent). Module source is not copied into this catalog.

  rapid7.com
• NIST NVDVulnerability recordCVE-2021-23758

  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.

  nvd.nist.gov
• Packet Storm SecurityCited referencehttp://packetstormsecurity.com/files/175677/AjaxPro-Deserialization-Remote-Code-Execution.html

  Packet Storm link already published on the finding.

  packetstormsecurity.com
• VulnCheck KEVConfirmed exploitationCVE-2021-23758

  Ajax.NET Professional (AjaxPro) contains a deserialization of untrusted data vulnerability that could allow for remote code execution via arbitrary .NET classes. The impacted product(s) could be end-of-life (EoL) and/or end-of-service (EoS). Users are advised to discontinue use a

  vulncheck.com

References

• Exploit · packetstormsecurity.com
• Exploit · blog.talosintelligence.com
• CISA note · github.com
• CISA note · nvd.nist.gov
• VulnCheck exploitation evidence · previdian.com
• Third Party Advisory · snyk.io
• US Government Resource · cisa.gov
• CISA note · cisa.gov
• CISA note · cisa.gov
• VulnCheck exploitation evidence · cisa.gov
• VulnCheck exploitation evidence · recordedfuture.com

Freshness

Last verified in this catalog Oct 17, 2026. Significant claims (KEV, EPSS, CVSS, affected ranges) come from the source rows above — open the original publisher for the authoritative advisory.