Exploited CVEs / Microsoft / CVE-2021-31196
CVE-2021-31196
Microsoft Exchange Server Information Disclosure Vulnerability. Exploitation in the wild is confirmed by CISA, not predicted. Federal agencies were required to remediate by 2024-09-11 (that deadline has passed); treat that date as the outer bound for your own environment. The fix is in the vendor advisory: Microsoft Security Update Guide (MSRC), linked below.
Risk summary
Actively exploited Microsoft Exchange Server vulnerability. Added to the CISA KEV catalog 2024-08-21.
Senserva AI Opinion for CVE-2021-31196
Microsoft Exchange Server carries an information disclosure flaw that enables remote code execution, and its KEV addition on 2024-08-21, roughly three years after the patch, confirms attackers still find and exploit unpatched Exchange in the wild. On-premises Exchange remains one of the most consequential systems to lose: it holds mail for the whole organization and often domain-privileged service accounts. High Severity, and the population at risk is every Exchange server that missed its 2021 cumulative updates.
Do this: Verify all on-premises Exchange servers are on current cumulative updates and decommission any forgotten legacy Exchange still domain-joined.
AI-generated from public data, 2026-07-07. Verify against the vendor advisory before acting.
Senserva AI Opinion and rich prompt for CVE-2021-31196
Copy this prompt into Claude, ChatGPT, or Copilot. The facts are included, sourced from this page.
Full tracking and change history for CVE-2021-31196
- Published
- 2024-08-21
- Last revised
- 2024-08-21
- Changes tracked
- 1
Published and last-revised dates are authoritative, from Microsoft MSRC (or the CISA KEV date-added). Senserva additionally records day-to-day changes from 2026-07-07, refreshed several times a day; the change count reflects that forward-only tracking.
CISA required action
Federal remediation due date: 2024-09-11 (past due).
Official fix for CVE-2021-31196
The authoritative fix and affected-version list are published by the vendor. Find the Exchange Server advisory on Microsoft Security Update Guide (MSRC).
Common questions about CVE-2021-31196
Is CVE-2021-31196 actively exploited?
Yes. CVE-2021-31196 was added to the CISA Known Exploited Vulnerabilities (KEV) catalog on 2024-08-21, which means exploitation in the wild has been confirmed, not predicted.
What is the CISA deadline and required action for CVE-2021-31196?
CISA set the federal remediation due date at 2024-09-11, which has passed; treat any unremediated system as overdue.
What fixes CVE-2021-31196?
The authoritative fix is in the vendor advisory: see Microsoft Security Update Guide (MSRC) for the patched Exchange Server versions and any workarounds. KEV listing makes this a fix-first item: patch it ahead of higher-CVSS issues nobody is exploiting.
Can I ask my own AI about CVE-2021-31196?
Yes. This page includes a free, ready-to-paste AI prompt containing CVE-2021-31196's key facts: severity, CVSS, EPSS, the KEV date, the CISA due date, and the required action. Copy it into Claude, ChatGPT, or Copilot; the data is refreshed twice a day (morning and afternoon US Central).
Scope and sources
- More exploited Microsoft CVEs
- CVE-2019-1068CVE-2008-4250CVE-2009-1537CVE-2010-0249CVE-2010-0806CVE-2026-41091CVE-2026-45498CVE-2026-33825
All Microsoft exploited CVEs on one page: Microsoft vulnerabilities actively exploited.
- Authoritative references
Every actively exploited CVE, searchable with due dates and CSV export: the exploited-CVE tracker. The newest additions: exploited this week.