CVE-2025-59249
Official description Straight from the sourceThe vendor's or NVD's own wording, published unedited. Authoritative, but often terse — it says what broke, rarely what to do.
NVD · uneditedWeak authentication in Microsoft Exchange Server allows an authorized attacker to elevate privileges over a network.
Technical summary Written by usOur analysis, written from the advisory, the CVSS vector and the affected-version data. It adds context the advisory leaves out, and never invents facts that are not in the source.
dbcve analysis · moderate confidenceA weak authentication vulnerability in Microsoft Exchange Server allows an authorized attacker to elevate privileges over the network. This appears to be a privilege escalation flaw where the authentication mechanism fails to properly restrict or validate authenticated session permissions, enabling a user with some access to gain higher-level privileges within the Exchange environment.
Verify against the referenced sources before acting — the references below are authoritative for this CVE, this summary is not.
Affected products & versions What the vendor confirmedThe version ranges the vendor confirmed as vulnerable. If your version sits inside a range here, treat yourself as exposed until you have upgraded.
NVD · CPE data= 2016= 2019< 15.02.2562.029CVSS breakdown How the score is builtThe industry scoring standard. It rates how the flaw is reached, what it takes to exploit, and what an attacker gains — the score is derived from those, not the other way round.
From the vector- Attack vector
- Network
- Complexity
- Low
- Privileges
- Low
- User interaction
- None
- Scope
- Unchanged
- Confidentiality
- High
- Integrity
- High
- Availability
- High
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
Am I affected? How to checkSteps we derive from the advisory and the affected-version data, so you can decide whether this CVE reaches your setup. They are a guide, not a scan — your own configuration is the authority.
dbcve checksWork through these to decide whether this CVE applies to you.
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Check installed Exchange Server versionRun 'Get-ExchangeServer | Format-List Name, Edition, AdminDisplayVersion' in Exchange Management Shell, or check registry key 'HKLM\SOFTWARE\Microsoft\ExchangeServer\v15\Setup' for 'Version' and 'Build Number'Affected if Version is 2016 or 2019, or Subscription Edition with build < 15.02.2562.029 (15.02.2562.029 or higher is fixed)
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Verify Basic Authentication statusRun 'Get-WebApplicationProxyHealthMonitor' or check authentication providers in IIS: 'appcmd list config /section:authentication' for ECP, OWA, EWS, and OAB virtual directories. Also run 'Get-OrganizationConfig | Format-List BasicAuth*'Affected if Basic Authentication is enabled on any Exchange virtual directory (Owa, Ecp, Ews, OAB, ActiveSync) without modern authentication enforced
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Check Modern Authentication configurationRun 'Get-OrganizationConfig | Format-List OAuth2ClientProfileEnabled, ModernAuthEnabled' in Exchange Management ShellAffected if Modern authentication is disabled (OAuth2ClientProfileEnabled = False or ModernAuthEnabled = False)
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Inspect Exchange authentication logon methodsOpen Exchange Admin Center > Servers > Virtual Directories > select each directory (OWA, ECP, EWS) > check 'Authentication' tab. Look for 'Basic authentication' checked while 'Windows authentication' or 'OAuth' is uncheckedAffected if Virtual directories allow logon using only username/password (Basic Auth) without requiring multi-factor or certificate-based authentication
Environment is affected if running an affected Exchange version (2016, 2019, or Subscription Edition < build 15.02.2562.029) AND Basic Authentication is enabled on Exchange virtual directories without Modern Authentication enforcement.
Generated from the published advisory. Verify against your own configuration.
Remediation Closing itWhat it takes to close this. Where a vendor fix exists we point at it; where none exists we say so plainly, and can build one. Effort estimates are scoped from the advisory, not from your codebase.
dbcve · scoped15.02.2562.029
Apply the vendor-supplied security update for Microsoft Exchange Server as soon as possible, after validating backup integrity and scheduling appropriate maintenance windows.
Install the Security Update or Cumulative Update containing the fix for CVE-2025-59249 (version 15.02.2562.029 or later for Subscription Edition; for Exchange Server 2016/2019, install the corresponding CU that includes this security fix)
- 1. Identify current Exchange Server version by running: Get-ExchangeServer | Format-List Name, Edition, AdminDisplayVersion
- 2. Review Microsoft Security Response Center (msrc.microsoft.com) for CVE-2025-59249 to obtain the specific Security Update or Cumulative Update number
- 3. Download the required Security Update from the Microsoft Update Catalog or Microsoft Download Center
- 4. On the Exchange Server, install the downloaded update: Run the .exe as administrator and follow the installation wizard
- 5. After installation, restart the Microsoft Exchange services or reboot the server
- 6. Verify the update was applied successfully by checking the version again: Get-ExchangeServer | Format-List Name, Edition, AdminDisplayVersion
- 7. Test Exchange services functionality (OWA, ECP, SMTP, etc.) to ensure normal operation
Generated from the published advisory — verify against the referenced sources before acting.
- Consultation6.0 h
- Implementation12.0 h
- Testing10.0 h
- Review / QA5.0 h
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Scan for this in your stack
Free · runs locallyCheck whether your project pulls in CVE-2025-59249 — or any other known-vulnerable package — straight from your lock files. Free and open source; it runs locally and uploads nothing.
References Go to the primary sourcePrimary sources — vendor advisories, patches and trackers. Where our summary and a reference disagree, the reference wins.
Primary sourcesPractitioner notes
ContributedPeer-ranked notes from engineers who’ve handled CVE-2025-59249 in production — separate from our analysis above.
The advisory tells you what broke. It rarely tells you what actually worked. If you’ve dealt with this one, that detail is what the next engineer is searching for.
- The version that genuinely resolved it — not the one the vendor claimed
- A config change or rule that shut the vector down
- A gotcha in the upgrade path that cost you an afternoon
No notes yet
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- Verified mitigations, workarounds, and config changes
- Version or environment caveats, and links to real fixes
- No weaponised exploit code, or anything meant to cause harm
- No spam, self-promotion, credentials, or personal data