CVE-2021-23758
CVE-2021-23758 is a high-severity vulnerability in Ajaxpro.2 Project Ajaxpro.2 with a CVSS 3.x base score of 8.1. It is listed in CISA's Known Exploited Vulnerabilities (KEV) catalog, confirming it has been exploited in the wild (added 2026-08-26). The underlying weakness is classified as CWE-502.
Key facts
- Severity: High (CVSS 3.x base score 8.1)
- CVSS v2: 7.5
- EPSS exploit prediction: 84% (100th percentile)
- Actively exploited: Yes — listed in CISA KEV (added 2026-08-26)
- Weakness: CWE-502
- Affected product: Ajaxpro.2 Project Ajaxpro.2
- Published:
- Last modified:
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.
Frequently asked questions
- What is CVE-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.
- How severe is CVE-2021-23758?
- CVE-2021-23758 has a CVSS 3.x base score of 8.1, rated high severity. It is exploitable over network with high attack complexity, requires no privileges and no user interaction. Impact on confidentiality is high, integrity high, and availability high.
- Is CVE-2021-23758 being actively exploited?
- Yes. CVE-2021-23758 is on CISA's Known Exploited Vulnerabilities (KEV) catalog, added on 2026-08-26, which means active exploitation has been confirmed. It should be prioritised for remediation.
- What products are affected by CVE-2021-23758?
- CVE-2021-23758 primarily affects Ajaxpro.2 Project Ajaxpro.2. In total, 2 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.
- How do I fix CVE-2021-23758?
- Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Because this CVE is known to be actively exploited, treat remediation as urgent — CISA KEV typically sets a short remediation deadline.
- When was CVE-2021-23758 published?
- CVE-2021-23758 was published on 2021-12-03 and last updated on 2026-08-27.
References
- http://packetstormsecurity.com/files/175677/AjaxPro-Deserialization-Remote-Code-Execution.html
- https://github.com/michaelschwarz/Ajax.NET-Professional/commit/b0e63be5f0bb20dfce507cb8a1a9568f6e73de57
- https://snyk.io/vuln/SNYK-DOTNET-AJAXPRO2-1925971
- https://blog.talosintelligence.com/uat-10147-chinese-speaking-adversary-integrates-agentic-ai-into-post-compromise-operations/
- https://www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2021-23758
Affected products (2)
- cpe:2.3:a:ajaxpro.2_project:ajaxpro.2:*:*:*:*:*:.net:*:*
- cpe:2.3:a:michaelschwarz:ajax.net_professional:*:*:*:*:*:.net:*:*
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