Page generated: 09 Nov 2026, 07:18 UTC
CVE-2021-26858
Microsoft Exchange Server Remote Code Execution Vulnerability
CVSS 7.8 (HIGH) KEV: KNOWN CATALOG
Attention and evidence
HYPE SCORE
0.0/10
REALITY · THREAT PRIORITY
8.6/10
General review priority; not probability
Evidence confidence: Exploitation recorded
Sources: 13 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
Barracuda Networks Blog
Press · 09 Dec 2025, 08:00 · Barracuda detects increased probing for Microsoft Exchange vulnerabilities - Barracuda Networks Blog
The Record from Recorded Future News
Press · 09 Jan 2023, 08:00 · Microsoft Exchange bugs top list of exploited vulnerabilities affecting financial sector - The Record from Recorded Future News
Qualys
Press · 06 May 2022, 07:00 · CISA Alert: Top 15 Routinely Exploited Vulnerabilities - Qualys
Ars Technica
Press · 17 Nov 2021, 08:00 · Hackers backed by Iran are targeting US critical infrastructure, US warns - Ars Technica
The Hacker News
Press · 29 Jul 2021, 07:00 · Top 30 Critical Security Vulnerabilities Most Exploited by Hackers - The Hacker News
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 8.6 (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 7.8; EPSS 93.7%
- Attention, last 30 days
- 0 distinct story titles; 0 press documents; 0 publisher domains.
- Technical potential
- local access, no prior privileges, user interaction.
- Observed activity
- Exploitation recorded in CISA KEV.
- Known scale
- Not quantified.
- Evidence confidence basis
- Trusted exploitation confirmation
Score evaluated: 2026-11-05 13:58:24.835925+00:00 · EPSS snapshot: 2026-11-05T12:03:04Z
Source event timeline
First press mention
02 Mar 2021, 08:00
Published
02 Mar 2021, 23:55
Added to the CISA KEV catalog
03 Nov 2021, 00:00
Latest press mention
09 Dec 2025, 08:00
Score calculated
05 Nov 2026, 13:58
PoCs on GitHub
2 repositories