Page generated: 08 Nov 2026, 14:29 UTC
CVE-2021-42321
Microsoft Exchange Server Remote Code Execution Vulnerability
CVSS 8.8 (HIGH) KEV: KNOWN CATALOG
Attention and evidence
HYPE SCORE
0.0/10
REALITY · THREAT PRIORITY
8.8/10
General review priority; not probability
Evidence confidence: Exploitation recorded
Sources: 11 documents and public datasets.
Hype components
Headline sample (25%)
0/100
Press, 30 days (60%)
0/100
Grounded branding (15%)
0/100
HYPE TOTAL0/100
Sources and documents
Help Net Security
Press · 20 Jan 2026, 08:00 · Initial access broker pleads guilty to selling access to 50 corporate networks - Help Net Security
The Record from Recorded Future News
Press · 03 Nov 2022, 07:00 · Microsoft accuses China of abusing vulnerability disclosure requirements - The Record from Recorded Future News
Arctic Wolf
Press · 22 Jul 2022, 17:43 · CVE-2021-42321 & CVE-2021-42292 - Arctic Wolf
Google Cloud
Press · 13 Dec 2021, 08:00 · Now You Serial, Now You Don’t — Systematically Hunting for Deserialization Exploits - Google Cloud
Cyberint
Press · 30 Nov 2021, 08:00 · Monthly Cyber Vulnerability Bulletin – November 2021 - Cyberint
Score evolution
● Hype ● Reality
Earlier evidence-support scores are retained in history; this chart shows only the current priority definition.
First record: hype 0.0 · reality 8.8 (2026-11-02 15:12). The curve appears once the score changes.
Public exploit evidence
2
Public exploit entries / repo candidates
Evidence context and dated references
Reality is general threat/review priority, combining observed exploitation, CVSS severity and fresh EPSS. Evidence confidence is separate. This is not calibrated risk, a victim count or an asset-specific assessment. A range reflects missing numeric inputs.
Evidence in context
- Confidence in exploitation evidence
- Exploitation recorded
- Priority basis
- Recorded exploitation; CVSS 8.8; EPSS 91.7%
- Attention, last 30 days
- 0 distinct story titles; 0 press documents; 0 publisher domains.
- Technical potential
- network access, low privileges, no user interaction.
- Observed activity
- Exploitation recorded in CISA KEV.
- Known scale
- Not quantified.
- Evidence confidence basis
- Trusted exploitation confirmation
Score evaluated: 2026-11-05 13:58:31.036516+00:00 · EPSS snapshot: 2026-11-05T12:03:04Z
Source event timeline
First press mention
09 Nov 2021, 08:00
Published
10 Nov 2021, 00:47
Added to the CISA KEV catalog
17 Nov 2021, 00:00
Latest press mention
20 Jan 2026, 08:00
Score calculated
05 Nov 2026, 13:58
PoCs on GitHub
2 repositories