How severe is CVE-2016-3378?

CVE-2016-3378 has a CVSS 3.x base score of 7.4, rated high severity. It is exploitable over network with low attack complexity, requires no privileges and user interaction. Impact on confidentiality is none, integrity high, and availability none.

Is CVE-2016-3378 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 15% (96th percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2016-3378?

CVE-2016-3378 primarily affects Microsoft Exchange Server. In total, 5 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.

How do I fix CVE-2016-3378?

Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its high severity, prioritise patching exposed systems.

When was CVE-2016-3378 published?

CVE-2016-3378 was published on 2016-09-14 and last updated on 2026-06-17.

CVE-2016-3378

CVE-2016-3378 is a high-severity vulnerability in Microsoft Exchange Server with a CVSS 3.x base score of 7.4. Its EPSS exploit-prediction score of 15% places it in the 96th percentile, indicating an elevated likelihood of exploitation. The underlying weakness is classified as CWE-20.

Key facts

Severity: High (CVSS 3.x base score 7.4)
CVSS v2: 5.8
EPSS exploit prediction: 15% (96th percentile)
Actively exploited: Not listed in CISA KEV
Weakness: CWE-20
Affected product: Microsoft Exchange Server
Published: 2016-09-14
Last modified: 2026-06-17

Description

Open 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."

Frequently asked questions

What is CVE-2016-3378?: Open 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."
How severe is CVE-2016-3378?: CVE-2016-3378 has a CVSS 3.x base score of 7.4, rated high severity. It is exploitable over network with low attack complexity, requires no privileges and user interaction. Impact on confidentiality is none, integrity high, and availability none.
Is CVE-2016-3378 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 15% (96th percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2016-3378?: CVE-2016-3378 primarily affects Microsoft Exchange Server. In total, 5 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.
How do I fix CVE-2016-3378?: Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its high severity, prioritise patching exposed systems.
When was CVE-2016-3378 published?: CVE-2016-3378 was published on 2016-09-14 and last updated on 2026-06-17.

References

Affected products (5)

cpe:2.3:a:microsoft:exchange_server:2013:cumulative_update_12:*:*:*:*:*:*
cpe:2.3:a:microsoft:exchange_server:2013:cumulative_update_13:*:*:*:*:*:*
cpe:2.3:a:microsoft:exchange_server:2013:sp1:*:*:*:*:*:*
cpe:2.3:a:microsoft:exchange_server:2016:cumulative_update_1:*:*:*:*:*:*
cpe:2.3:a:microsoft:exchange_server:2016:cumulative_update_2:*:*:*:*:*:*

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