CVE-2021-23758Deserialization of Untrusted Data
Updated under an hour ago ()
Does this affect you?
It affects ajaxpro.2_project ajaxpro.2 and 1 other product. Add what you run to find out whether that includes you.
CISA lists it as known exploited since Aug 26, 2026; federal agencies had to remediate by Sep 9, 2026. Treat that date as your deadline.
Do this next
Free account, 1 product
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.
- CVSS
- 8.1 HIGH (v3.1, CNA)CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H
- Weakness (CWE)
- CWE-502
- Known exploited
- Added to CISA KEV Aug 26, 2026; federal remediation due Sep 9, 2026Apply 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.
- EPSS (exploitation in the next 30 days)
- 82.58% (percentile 100)
- Assigned by
- snyk
- NVD analysis
- Analyzed
- Record last updated
- Aug 27, 2026
- First seen by InfoSec Signals
- Oct 9, 2026
Affected products
ajaxpro.2_project ajaxpro.2 ajaxpro.2_project:ajaxpro.2 | all versions | NVD |
michaelschwarz ajax.net_professional michaelschwarz:ajax.net_professional | before 21.10.30.1 | NVD |
References
- https://snyk.io/vuln/SNYK-DOTNET-AJAXPRO2-1925971third-party-advisory
- https://github.com/michaelschwarz/Ajax.NET-Professional/commit/b0e63be5f0bb20dfce507cb8a1a9568f6e73de57patch, third-party-advisory
- http://packetstormsecurity.com/files/175677/AjaxPro-Deserialization-Remote-Code-Execution.htmlexploit, vdb-entry
- https://blog.talosintelligence.com/uat-10147-chinese-speaking-adversary-integrates-agentic-ai-into-post-compromise-operations/exploit, third-party-advisory
- https://www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2021-23758us-government-resource
The CVE record on cve.org NVD's entry
The CVE record is authoritative. Products marked “from the name” were identified from the CNA's free-text names, not a CPE, and are matched less certainly. This product uses the NVD API but is not endorsed or certified by the NVD.