Vulnerability report

Exploited in the wild Confirmed confidence In CISA KEV

CVE-2026-42897

Microsoft Exchange Server Spoofing Vulnerability

Microsoft Exchange Server 2016 Cumulative Update 23 · affected before 15.01.2507.069

Watch CVE-2026-42897 Browse KEV feed
Severity
CVSS 8.1 · High
Confidence
Confirmed
Exploit status
Exploited in the wild
EPSS
0.5%
First observed
—
Last observed
—

Decision summary

What security teams need to know first

Direct answers before the deeper technical record.

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...

Is it exploited?

Yes. Previdian tracks this CVE as a known exploited vulnerability. Confidence is confirmed. Listed in CISA KEV. Also confirmed by third-party sources.

Who is affected?

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.

Microsoft Affected
Microsoft Exchange Server 2016 Cumulative Update 23
Before 15.01.2507.069
Microsoft Affected
Microsoft Exchange Server 2019 Cumulative Update 14
Before 15.02.1544.041
Microsoft Affected
Microsoft Exchange Server 2019 Cumulative Update 15
Before 15.02.1748.046
Microsoft Affected
Microsoft Exchange Server Subscription Edition RTM
Before 15.02.2562.043
View vendor advisory (opens in new tab)
Published
14 May 2026
Exploitation Reported
01 Jun 2026
Attack vector
Remote
Complexity
Low
Privileges
None
User interaction
Required

Tags

cisa microsoft

CVE References

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

Recorded 01 Jun 2026

A trusted third party reported exploitation.

Known exploited vulnerability sources

Per-source evidence links for KEV attestations are available through the Previdian Pro API.

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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
User-Agents
Callback hosts
0
0
0

Request targets and User-Agents available in Pro. Callback host details available in 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

8.1 High

Potential damage if exploited. Separate from whether attackers are using it.

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

0.5%

Estimated chance of exploitation in the next 30 days. Previdian's warning comes from evidence, not this score.

Weaknesses

Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting') CWE-79

Recent mention · The Hacker News

Three Threat Groups Target Russian Enterprises With Backdoors, Ransomware, and Wipers

Enterprises in Russia have emerged as the target of three threat activity clusters tracked as NightEagle, Hacking Cat, and Toy Ghouls, according to multiple reports from Kaspersky. The cybersecurity vendor said it has identified attacks mounted by NightEagle (aka APT-Q-95), a...

Read full advisory

Timeline

From disclosure to observed exploitation

  1. 14:00 UTC

    Added to CISA KEV

    Listed in the CISA Known Exploited Vulnerabilities catalog

  2. 13:29 UTC

    Added to Previdian KEV Feed

    High-confidence, third-party attested exploitation

  3. 17:00 UTC

    CVE published

    Vulnerability disclosed publicly

  4. 22:35 UTC

    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.

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  • 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

Sample API response 
{
  "cve_id": "CVE-2026-42897",
  "confidence": "Confirmed",
  "cvss_score": 8.1,
  "cvss_estimated": false,
  "epss_score": 0.00519,
  "exploit_status": {
    "exploited_in_the_wild": true,
    "active_exploitation_observed": false
  },
  "sensor_telemetry": { "attempts": 0, "sensors": 0 }
}