Exploited· due 2026-09-098.1highHigh

CVE-2021-23758

Ajaxpro.2 Project Ajaxpro.2

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.

Exploitation status

CISA has confirmed this is being exploited in the wild. That is an observation of real attacks, not a prediction.
US federal civilian agencies are required to remediate it by 2026-09-09. That deadline does not bind private companies, but it is a reasonable benchmark for how urgently CISA views it.
A vendor advisory or patch reference has been published.

Required action

Apply 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.

CISA’s wording, unedited.

What the metrics mean

It is reachable over a network, without needing local access.
For an attacker who can reach it, exploitation depends on conditions outside the attacker's control.
To exploit it, no account is needed.
Beyond that, no action by a user is required.

Scoring

CVSS: 8.1 (v3.1)
Vector: CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H
Weakness: CWE-502
Assigned by: report@snyk.io

Dates

Published: 2021-12-03
Last modified: 2026-08-27
Added to KEV: 2026-08-26
Remediation due: 2026-09-09
Sources: CISA KEV, NVD

Affected products

Ajaxpro.2 Project Ajaxpro.2all versions
Michaelschwarz Ajax.Net Professional- 21.10.30.1

As listed in the NVD configuration data. Not a statement about your estate.