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CVE-2026-45503

Microsoft Exchange Server Information Disclosure Vulnerability

No known exploitation. EPSS puts it in the 39th percentile. Fixed versions are out.

CVSS 3.18.1HighEPSS percentile39th0.4% chance in 30 daysCISA KEVNot listedNo confirmed exploitation
No public exploit knownFix5 products5 fixed builds listed below
Check it yourself

OpenVAS · 4 checks

e.g. OID 1.3.6.1.4.1.25623.1.0.119372

Run the check

Published Updated Sources: CVE.org, NVD, BDU

NVD CVE.org

What to do

Find your product and version, then upgrade to the build on the right.

  • Microsoft Exchange Server 2019 Cumulative Update 14Affected: ≥ 15.02.0.0, < 15.02.1544.043Upgrade to: 15.02.1544.043Stated by: CVE record
  • Microsoft Exchange Server 2016 Cumulative Update 23Affected: ≥ 15.01.0.0, < 15.01.2507.071Upgrade to: 15.01.2507.071Stated by: CVE record
  • Microsoft Exchange Server Subscription Edition RTMAffected: ≥ 15.02.0.0, < 15.02.2562.045Upgrade to: 15.02.2562.045Stated by: CVE record
  • Microsoft Exchange Server 2019 Cumulative Update 15Affected: ≥ 15.02.0.0, < 15.02.1748.048Upgrade to: 15.02.1748.048Stated by: CVE record
  • Microsoft Exchange Server Subscription EditionAffected: < 15.02.2562.043Upgrade to: 15.02.2562.043Stated by: NVD

Versions as the sources state them. Full version matrix after sign-in

Check it yourselfA free OpenVAS check exists for this CVE. Run it against your hosts.Is your organisation exposed?Request an assessment to establish which checks fit your systems.

What it is

From the CVE record

Improper authorization in Microsoft Exchange Server allows an authorized attacker to disclose information over a network.

In plain language

No plain-language summary for this CVE yet.

Exploitation

Where each signal puts this CVE on the scale from published to confirmed exploited.

EPSS39th
CISA KEV

Not in the catalog. CISA has not confirmed exploitation.

Public exploits

No public exploit or proof of concept found in the sources we track.

EPSS

0.4% chance of exploitation activity in the next 30 days, which ranks it in the 39th percentile of scored CVEs.

Exploit Prediction Scoring System, FIRST.org. A probability, not a confirmation.

Lifecycle

12 events over 49 days, from the signal feeds we watch.

  1. Patch availablerecord updated
  2. Patch availablerecord updated
  3. Patch availablerecord updated
  4. OpenVAS check added
  5. Patch availablerecord updated
  6. Publishedweakness classified, att&ck mapped

Affected products

And 4 more affected products. See all after sign-in

Technical detail

CVSS 3.1 vector

Open in the CVSS calculator

CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:N

Scored 8.1 by NVD.

How it is reached

  • Attack Vector NetworkExploitable remotely over the network without any special conditions
  • Attack Complexity LowNo special conditions — the attack can be reliably reproduced
  • Privileges Required LowRequires basic user-level privileges
  • User Interaction NoneNo user interaction needed — fully automated exploitation

Scope

  • Scope UnchangedImpact is limited to the vulnerable component itself

Impact if exploited

  • Confidentiality HighTotal information disclosure — all data in the component is compromised
  • Integrity HighTotal loss of integrity — attacker can modify any data in the component
  • Availability NoneNo availability impact

Weaknesses

ATT&CK techniques

Mapped from the weaknesses above (CWE to ATT&CK), not observed in attacks.

Sources

References in the record

In the news

Watch the software you run.

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We'll flag the next CVE, public exploit or patch for Microsoft Corp, not every advisory.