What it is
CVE-2023-21529 is Microsoft Exchange Server Remote Code Execution Vulnerability.
Vulnerability report
Exploited in the wild
Confirmed confidence
In CISA KEV
CVE-2023-21529
Microsoft Exchange Server Remote Code Execution Vulnerability
Microsoft / Microsoft Exchange Server 2013 Cumulative Update 23 · affected before 15.00.1497.047
- Severity
- CVSS 8.8 · High
- Confidence
- Confirmed
- Exploit status
- Exploited in the wild
- EPSS
- 62.1%
- First observed
- —
- Last observed
- —
Decision summary
What security teams need to know first
Direct answers before the deeper technical record.
Is it exploited?
Yes. Previdian tracks this CVE as a known exploited vulnerability. Confidence is confirmed.
Who is affected?
Microsoft / Microsoft Exchange Server 2013 Cumulative Update 23 affected before 15.00.1497.047.
What should we do?
Prioritize remediation. Validate affected assets and apply vendor fixes on an accelerated timeline.
Overview
Microsoft Exchange Server Remote Code Execution Vulnerability
Microsoft Exchange Server Remote Code Execution Vulnerability
Vendor
Product
Affected
Status
Microsoft
Microsoft Exchange Server 2013 Cumulative Update 23
Before 15.00.1497.047
Affected
Microsoft
Microsoft Exchange Server 2016 Cumulative Update 23
Before 15.01.2507.021
Affected
Microsoft
Microsoft Exchange Server 2019 Cumulative Update 11
Before 15.02.0986.041
Affected
Microsoft
Microsoft Exchange Server 2019 Cumulative Update 12
Before 15.02.1118.025
Affected
- Published
- 14 Feb 2023
- Exploitation Reported
- 01 Jun 2026
- Attack vector
- Remote
- Complexity
- Low
- Privileges
- Low
- User interaction
- None
Tags
cisa
microsoft
malware
CVE References
- CVE Record CVE.org · CVE Record https://www.cve.org/CVERecord?id=CVE-2023-21529
- Microsoft Exchange Server Remote Code Execution Vulnerability msrc.microsoft.com · Vendor Advisory https://msrc.microsoft.com/update-guide/vulnerability/CVE-2023-21529
Exploitation evidence
Why Previdian marks this CVE as exploited
Third-party attestation and first-party sensor observation are shown separately so teams can judge the evidence chain.
Exploited in the wild
CVE
Independent exploitation attestation added to the Previdian record.
Used in malware
CVE
Malware families have been linked to exploitation of this CVE.
Known exploited vulnerability sources
Per-source evidence links for KEV attestations are available through the Previdian Pro API.
Learn about Pro API access| Source | Added |
|---|---|
| CVE First | 2026-06-01 13:07 UTC |
| CISA | 2026-06-02 14:02 UTC |
Detection
Operational artifacts and observed signals
Make the evidence actionable in scanner, SOC, and edge-control workflows.
Observed signals
- Request targets
- 0
- User-Agents
- 0
Raw values available in Pro and Enterprise.
Scanner coverage
No scanner integrations recorded yet.
Virtual patch status
No Previdian virtual patch is currently available. Future rules ship for ModSecurity, Cloudflare, and AWS WAF.
Learn about virtual patches →No detection artifacts or sensor request patterns are available for this CVE yet.
Check back as sensor telemetry and scanner integrations are updated.
Risk and context
Severity, weaknesses, and research context
CVSS v3.1
8.8
High
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H/E:U/RL:O/RC:C
EPSS
62.1%
Weaknesses
Timeline
From disclosure to observed exploitation
-
First public exploitation report
Exploit observed in malware
-
Added to CISA KEV
Listed in the CISA Known Exploited Vulnerabilities catalog
-
Added to Previdian KEV Feed
High-confidence, third-party attested exploitation
-
CVE published
Vulnerability disclosed publicly
-
CVE ID reserved
Identifier reserved by the CNA
Pro API
Automate this intelligence
Confidence, exploit status, sensor telemetry, PoCs, scanner integrations, mentions, and tags are available programmatically for VM, SOC, and CTI workflows.
- Evidence confidence and provenance
- First-party sensor telemetry
- PoC and scanner references
- Affected versions and enrichment
- Automation-ready JSON delivery
GET /api/v2/pro/kevs/CVE-2023-21529
Free JSON includes basic KEV fields{
"cve_id": "CVE-2023-21529",
"confidence": "Confirmed",
"cvss_score": 8.8,
"cvss_estimated": false,
"epss_score": 0.62104,
"exploit_status": {
"exploited_in_the_wild": true,
"active_exploitation_observed": false
},
"sensor_telemetry": { "attempts": 0, "sensors": 0 }
}Early warning alerts
Get alerts on high-impact exploitation
Receive curator-selected alerts when exploitation activity warrants attention. Each alert includes the evidence and context needed to decide what requires attention now.