What it is
CVE-2026-42897 is an unauthenticated Microsoft Exchange Server Spoofing Vulnerability. Improper neutralization of input during web page generation ('cross-site scripting') in Microsoft Exchange Server allows an...
Vulnerability report
Exploited in the wild
Confirmed confidence
In CISA KEV
CVE-2026-42897
Microsoft Exchange Server Spoofing Vulnerability
Microsoft / Microsoft Exchange Server 2016 Cumulative Update 23 · affected before 15.01.2507.069
- Severity
- CVSS 8.1 · High
- Confidence
- Confirmed
- Exploit status
- Exploited in the wild
- EPSS
- 70.3%
- First observed
- —
- Last observed
- —
Decision summary
What security teams need to know first
Direct answers before the deeper technical record.
Is it exploited?
Yes. KEV Intelligence tracks this CVE as a known exploited vulnerability. Confidence is confirmed.
Who is affected?
Microsoft / Microsoft Exchange Server 2016 Cumulative Update 23 affected before 15.01.2507.069.
What should we do?
Prioritize remediation. Validate affected assets and apply vendor fixes on an accelerated timeline.
Overview
Microsoft Exchange Server Spoofing Vulnerability
Improper neutralization of input during web page generation ('cross-site scripting') in Microsoft Exchange Server allows an unauthorized attacker to perform spoofing over a network.
Vendor
Product
Affected
Status
Microsoft
Microsoft Exchange Server 2016 Cumulative Update 23
Before 15.01.2507.069
Affected
Microsoft
Microsoft Exchange Server 2019 Cumulative Update 14
Before 15.02.1544.041
Affected
Microsoft
Microsoft Exchange Server 2019 Cumulative Update 15
Before 15.02.1748.046
Affected
Microsoft
Microsoft Exchange Server Subscription Edition RTM
Before 15.02.2562.043
Affected
- Published
- 14 May 2026
- Exploitation Reported
- 01 Jun 2026
- Attack vector
- Remote
- Complexity
- Low
- Privileges
- None
- User interaction
- Required
Tags
cisa
microsoft
CVE References
- CVE Record CVE.org · CVE Record https://www.cve.org/CVERecord?id=CVE-2026-42897
- Microsoft Exchange Server Spoofing Vulnerability msrc.microsoft.com · Vendor Advisory https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-42897
Exploitation evidence
Why KEV Intelligence 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 KEV Intelligence record.
Known exploited vulnerability sources
Per-source evidence links for KEV attestations are available through the KEV Intelligence Pro API.
Learn about Pro API access| Source | Added |
|---|---|
| CVE First | 2026-06-01 13:29 UTC |
| CISA | 2026-06-02 14:00 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 KEV Intelligence 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
8.1
High
CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:N/E:F/RL:O/RC:C
EPSS
70.3%
Timeline
From disclosure to observed exploitation
-
Added to CISA KEV
Listed in the CISA Known Exploited Vulnerabilities catalog
-
Added to KEV Intelligence 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-2026-42897
Free JSON includes basic KEV fields{
"cve_id": "CVE-2026-42897",
"confidence": "Confirmed",
"cvss_score": 8.1,
"cvss_estimated": false,
"epss_score": 0.70307,
"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.