CVE-2021-23758Vulnerability
Ajax.NET Professional Deserialization of Untrusted Data Vulnerability
Exploited in the wildCISA added it to its Known Exploited Vulnerabilities list on .
Reported by 2 independent sources · first reported by Infosecurity Magazine · last reported
Last reported 1 month ago
CISA KEVAdded 26 Aug 2026
Fix due 9 Sep 2026
Used by ransomware: not knownCISA KEV catalogue
Fix due 9 Sep 2026
Used by ransomware: not knownCISA KEV catalogue
EPSS82.6%
higher than 99% of CVEsFIRST EPSS, as of 21 Oct 2026
higher than 99% of CVEsFIRST EPSS, as of 21 Oct 2026
What the reports say
2 reports, newest first · the exact sentence from each-
August 2026 CVE Landscape“CVE-2021-23758”
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CISA Warns of Six Exploited Flaws in Microsoft, Linux, Red Hat and Citrix Products“CVE-2021-23758: Ajax.NET professional deserialization of untrusted data vulnerability (CVSS rating: 8.1)”
Indicators reported together
named in the same reportsAlso named with it: CVE-2015-3246, CVE-2015-5287, CVE-2019-1068, CVE-2022-0995, CVE-2026-8452, CVE-2025-49113, CVE-2026-68820, CVE-2026-65400, CVE-2026-60004, CVE-2026-64849, CVE-2026-33824, CVE-2026-0300, CVE-2026-33017, CVE-2017-0199, CVE-2022-0847, CVE-2026-34486, CVE-2026-39987, CVE-2026-63030, CVE-2021-3156, CVE-2021-29441
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