CVE-2016-3378
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 · uneditedOpen redirect vulnerability in Microsoft Exchange Server 2013 SP1, 2013 Cumulative Update 12, 2013 Cumulative Update 13, 2016 Cumulative Update 1, and 2016 Cumulative Update 2 allows remote attackers to redirect users to arbitrary web sites and conduct phishing attacks via a crafted URL, aka "Microsoft Exchange Open Redirect Vulnerability."
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 · high confidenceOpen redirect vulnerability in Microsoft Exchange Server web interfaces (OWA and ECP) allows attackers to craft malicious URLs that transparently redirect authenticated users to arbitrary external websites, enabling credential theft and phishing campaigns.
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= 2013= 2016CVSS 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
- None
- User interaction
- Required
- Scope
- Changed
- Confidentiality
- None
- Integrity
- High
- Availability
- None
CVSS:3.0/AV:N/AC:L/PR:N/UI:R/S:C/C:N/I:H/A:N
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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Confirm Exchange Server is installedCheck for Microsoft Exchange Server services (such as MSExchangeIS, MSExchangeTransport) or examine the installation directory at Program Files\Microsoft\Exchange Server. Alternatively, run Get-ExchangeServer in Exchange Management Shell if available.Affected if Exchange Server is not present on the system
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Identify the Exchange Server versionRun Get-ExchangeServer | Format-List Name,AdminDisplayVersion in Exchange Management Shell, or check the version in the registry under HKLM\SOFTWARE\Microsoft\ExchangeServer\v15\SetupVersion. Exchange 2013 shows version 15.0.x.x and Exchange 2016 shows version 15.1.x.x.Affected if The version is Exchange Server 2013 (15.0) or Exchange Server 2016 (15.1)
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Determine the installed Cumulative UpdateExamine the full version build number from the previous step. For Exchange 2013, extract the third segment (e.g., 1155 = CU13). For Exchange 2016, extract the third segment (e.g., 466 = CU2). Compare against CU14 for Exchange 2013 and CU3 for Exchange 2016.Affected if Exchange 2013 is below Cumulative Update 14 (build < 15.0.1155) or Exchange 2016 is below Cumulative Update 3 (build < 15.1.466)
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Verify OWA or ECP virtual directories existRun Get-OwaVirtualDirectory -Server <servername> and Get-EcpVirtualDirectory -Server <servername> in Exchange Management Shell to list the configured web applications.Affected if OWA or ECP virtual directories are configured and the server is running a vulnerable Exchange version
The server is affected if it runs Exchange Server 2013 Cumulative Update lower than 14 or Exchange Server 2016 Cumulative Update lower than 3, with OWA or ECP virtual directories enabled.
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.
From vendor dataApply the relevant Microsoft security update (MS16-108) or upgrade to Exchange 2013 Cumulative Update 14+ / Exchange 2016 Cumulative Update 3+ to eliminate the vulnerable URL parsing code path.
- Consultation2.0 h
- Implementation4.0 h
- Testing3.0 h
- Review / QA1.0 h
An estimate, not a bill — we confirm scope with you before any work starts. Need it this week? Rush from $2,800.
Scan for this in your stack
Free · runs locallyCheck whether your project pulls in CVE-2016-3378 — 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-2016-3378 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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A place for practitioners to share what actually worked: a mitigation you’ve tested, a configuration change, a version- or environment-specific caveat, or a link to a verified patch. The most useful notes rise to the top as peers upvote them, so the signal stays high.
- 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