How severe is CVE-2019-1233?

CVE-2019-1233 has a CVSS 3.x base score of 7.5, rated high severity. It is exploitable over network with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is none, integrity none, and availability high.

Is CVE-2019-1233 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 6% (93rd percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2019-1233?

CVE-2019-1233 primarily affects Microsoft Exchange Server. In total, 4 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.

How do I fix CVE-2019-1233?

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-2019-1233 published?

CVE-2019-1233 was published on 2019-09-11 and last updated on 2026-06-17.

CVE-2019-1233

CVE-2019-1233 is a high-severity vulnerability in Microsoft Exchange Server with a CVSS 3.x base score of 7.5. It is not currently listed as actively exploited by CISA, and its EPSS exploit-prediction score is low.

Key facts

Severity: High (CVSS 3.x base score 7.5)
CVSS v2: 7.8
EPSS exploit prediction: 6% (93rd percentile)
Actively exploited: Not listed in CISA KEV
Affected product: Microsoft Exchange Server
Published: 2019-09-11
Last modified: 2026-06-17

Description

A denial of service vulnerability exists in Microsoft Exchange Server software when the software fails to properly handle objects in memory, aka 'Microsoft Exchange Denial of Service Vulnerability'.

Frequently asked questions

What is CVE-2019-1233?: A denial of service vulnerability exists in Microsoft Exchange Server software when the software fails to properly handle objects in memory, aka 'Microsoft Exchange Denial of Service Vulnerability'.
How severe is CVE-2019-1233?: CVE-2019-1233 has a CVSS 3.x base score of 7.5, rated high severity. It is exploitable over network with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is none, integrity none, and availability high.
Is CVE-2019-1233 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 6% (93rd percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2019-1233?: CVE-2019-1233 primarily affects Microsoft Exchange Server. In total, 4 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.
How do I fix CVE-2019-1233?: 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-2019-1233 published?: CVE-2019-1233 was published on 2019-09-11 and last updated on 2026-06-17.

References

https://portal.msrc.microsoft.com/en-US/security-guidance/advisory/CVE-2019-1233

Affected products (4)

cpe:2.3:a:microsoft:exchange_server:2016:cumulative_update_12:*:*:*:*:*:*
cpe:2.3:a:microsoft:exchange_server:2016:cumulative_update_13:*:*:*:*:*:*
cpe:2.3:a:microsoft:exchange_server:2019:cumulative_update_1:*:*:*:*:*:*
cpe:2.3:a:microsoft:exchange_server:2019:cumulative_update_2:*:*:*:*:*:*

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