Risk Letters

Exploited vulnerability

CVE-2021-23758

TLP:CLEAR

Ajax.NET Professional Deserialization of Untrusted Data Vulnerability

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.

Facts

  • Vendor: Ajax.NET Professional
  • Product: Ajax.NET Professional
  • CVSS: 8.1
  • EPSS (probability of exploitation within 30 days): 82.6 %
  • On CISA's Known Exploited Vulnerabilities list since: 26 August 2026
  • First known exploitation: 26 August 2026
  • CISA's deadline for US federal agencies: 9 September 2026
  • Weakness: CWE-502
  • First seen by Risk Letters: 26 August 2026

Members see which Nordic sectors the flaw hits, and what to do about it.

Get the full brief

Data: NVD (public domain), CISA KEV, FIRST EPSS, MITRE ATT&CK, AlienVault OTX. NVD