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CVE-2026-42897

Microsoft Exchange Server Spoofing Vulnerability

MEDIUM
6.1
CVSS Score
Published: May 14, 2026 at 05:00 PM UTC
Updated: August 10, 2026 at 03:40 PM UTC
2 products affected across 1 vendorExchange ServerExchange Server Subscription Edition

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Severity
MEDIUM6.1
Exploitation
CISA KEV
Exploit prediction
EPSS 71%
SSVC
Active

Actively Exploited

CISA Known Exploited Vulnerabilities (KEV) Catalog

EPSS Score70.7%

EPSS (Exploit Prediction Scoring System) estimates a 70.7% chance this CVE is exploited in the wild within the next 30 days — higher than 99% of all CVEs. It complements CVSS: a high EPSS on a mid-severity CVE can still be urgent.

Microsoft Exchange Server contains a cross-site scripting vulnerability during web page generation in Outlook Web Access and when certain interaction conditions are met, arbitrary JavaScript can be executed in the browser context.

Required Action
Apply mitigations per vendor instructions, follow applicable BOD 22-01 guidance for cloud services, or discontinue use of the product if mitigations are unavailable.
Ransomware Use
Unknown
Added to KEV
May 15, 2026
Remediation Due
May 29, 2026
150 days overdue
Notes
https://msrc.microsoft.com/update-guide/en-US/vulnerability/CVE-2026-42897
https://learn.microsoft.com/en-us/exchange/plan-and-deploy/post-installation-tasks/security-best-practices/exchange-emergency-mitigation-service
https://nvd.nist.gov/vuln/detail/CVE-2026-42897

Description

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.

Affected

Our own answer: ranges merged, affected separated from platform-only, with confidence and review flags.

Exchange Server· Microsoft
95%
15.01.0.0 ≤ v < 15.01.2507.06915.02.0.0 ≤ v < 15.02.1544.04115.02.0.0 ≤ v < 15.02.1748.04615.01.0.015.02.0.020162016 cumulative_update_12016 cumulative_update_102016 cumulative_update_112016 cumulative_update_122016 cumulative_update_132016 cumulative_update_142016 cumulative_update_152016 cumulative_update_162016 cumulative_update_172016 cumulative_update_182016 cumulative_update_192016 cumulative_update_22016 cumulative_update_202016 cumulative_update_212016 cumulative_update_222016 cumulative_update_232016 cumulative_update_32016 cumulative_update_42016 cumulative_update_52016 cumulative_update_62016 cumulative_update_72016 cumulative_update_82016 cumulative_update_920192019 cumulative_update_12019 cumulative_update_102019 cumulative_update_112019 cumulative_update_122019 cumulative_update_132019 cumulative_update_142019 cumulative_update_22019 cumulative_update_32019 cumulative_update_42019 cumulative_update_52019 cumulative_update_62019 cumulative_update_72019 cumulative_update_82019 cumulative_update_9
Affected range stops below 15.01.2507.069, so it looks safe — our inference, not a vendor statement
Affected range stops below 15.02.1544.041, so it looks safe — our inference, not a vendor statement
Affected range stops below 15.02.1748.046, so it looks safe — our inference, not a vendor statement
Exchange Server Subscription Edition· Microsoft
95%
v < 15.02.2562.04315.02.0.0 ≤ v < 15.02.2562.04315.02.0.0
Affected range stops below 15.02.2562.043, so it looks safe — our inference, not a vendor statement

Remediation

No guide yet

No remediation guidance has been written for this CVE yet. What the record does show:

Patch and advisory references

References (2)

Vendor AdvisoryPatchMitigation
Source: cverecord
https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-42897
US Government Resource
Source: 134c704f-9b21-4f2e-91b3-4a467353bcc0
https://www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2026-42897

SSVC — Action Prioritization

SSVCActiveNot automatableTotal impact

SSVC signals action urgency (what to patch first), separate from CVSS which measures severity.

CVSS

6.1MEDIUM[email protected]
Attack Vector
NETWORK
Complexity
LOW
Privileges
NONE
User Interaction
REQUIRED
Scope
CHANGED
Confidentiality
LOW
Integrity
LOW
Availability
NONE
Vector?

Quick Info

StatusANALYZED
CWE
CWE-79

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