August 26, 2026 · Applied Cybernetics Group
CVE-2021-23758 — Ajax.NET Professional Ajax.NET Professional
Ajax.NET Professional Deserialization of Untrusted Data Vulnerability
- Added to KEV
2026-08-26- Federal due date
2026-09-09- Vendor
- Ajax.NET Professional
- Product
- Ajax.NET Professional
- EPSS
- 99.7th percentile (score 0.836, as of
2026-09-16) - NVD CVSS v3.1
- 8.1 (HIGH)
- Ransomware use
- Unknown
- Upstream
- https://nvd.nist.gov/vuln/detail/CVE-2021-23758
CISA short description
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.
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.
NVD 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.