CVE-2021-23758
Ajax.NET Professional — Ajax.NET Professional Deserialization of Untrusted Data Vulnerability
Ajax.NET Professional · in CISA KEV since 2026-08-26
CISA federal deadline · Overdue by 43 daysCISA KEVActively Exploited
87
EVRS 87 of 100 Immediate
Patch Immediately
Rank 300 of 2,960 tracked
Why it scores 87
Evidence available: 6 of 7 signalsListed in the CISA KEV catalog, and an EPSS probability of 0.826.
- CISA KEVApplied
- RansomwareDid not apply
- Vendor exploitationDid not apply
- EPSSApplied
- Microsoft Exploitability IndexNot applicable
- Pre-patch disclosureNo data
- KEV recencyApplied
- CVSSApplied
The band answers “how soon”, not “how bad”. No data for: Pre-patch disclosure. Why some signals show no data
Fix
No fixed version identified yetEvidence
Each value with its source| Measure | Value | Source |
|---|---|---|
| CVSS base scoreHow severe the flaw is in itself. It does not say how likely an attack is. | 9.8 | NVD |
| FIRST EPSSFIRST's estimate of the chance this is exploited in the next 30 days, and how that ranks against all CVEs. | 0.826 (99.67th pctl) | FIRST EPSS |
| Actively exploitedWhether a source of record has confirmed attacks using it in the wild. | Confirmed | CISA KEV |
| Ransomware campaign useWhether CISA has seen ransomware operators use it. | Unknown or none | CISA KEV |
| CISA remediation deadlineThe date US federal agencies must have fixed or mitigated it. | 2026-09-09 · CISA federal deadline · Overdue by 43 days | CISA KEV |