---
title: "Security digest: December 3, 2021"
url: https://erroneo.us/security/2021-12-03/
description: "December 3, 2021 vulnerability digest: 1 brief (AjaxPro CVE-2021-23758: Old ASP.NET RCE Now in…). What to patch and who can relax."
type: security-digest-day
section: "Security Digest"
date_published: 2021-12-03
date_modified: 2026-08-26
publisher: erroneo.us
author: erroneo.us Security Desk
license: All rights reserved. Quote with attribution and a link.
---

# Security digest: December 3, 2021

1 editorial brief.

## Take stock

- Check exposure: AjaxPro CVE-2021-23758: Old ASP.NET RCE Now in CISA KEV . Owners of ASP.NET Web Forms applications, in-house or bought from a vendor, that bundle AjaxPro.2.dll or register the ajaxpro/*.ashx handler, most urgently on internet-facing servers.
- None of it touches your stack? Then there is nothing to do today. That is a result, not a failure to read carefully.

## Editorial briefs

- **Check exposure** [AjaxPro CVE-2021-23758: Old ASP.NET RCE Now in CISA KEV](https://erroneo.us/security/briefs/ajaxpro-deserialization-rce-cve-2021-23758/index.md): If an ASP.NET app you run still ships AjaxPro, treat it as an unauthenticated RCE and upgrade or remove the library now; if you never used AjaxPro, there is nothing to do.

## Known exploited (CISA KEV)

None.

## Critical advisories

None.

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Source page: https://erroneo.us/security/2021-12-03/ · Security Digest: https://erroneo.us/security/ · More: https://erroneo.us/llms.txt