How severe is CVE-1999-1033?

CVE-1999-1033 has a CVSS 2.0 base score of 5.0, rated medium severity.

Is CVE-1999-1033 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 18% (97th percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-1999-1033?

CVE-1999-1033 primarily affects Microsoft Outlook Express. In total, 3 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.

How do I fix CVE-1999-1033?

Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround.

When was CVE-1999-1033 published?

CVE-1999-1033 was published on 1999-05-11 and last updated on 2026-06-16.

CVE-1999-1033

CVE-1999-1033 is a medium-severity vulnerability in Microsoft Outlook Express with a CVSS 2.0 base score of 5.0. Its EPSS exploit-prediction score of 18% places it in the 97th percentile, indicating an elevated likelihood of exploitation.

Key facts

Severity: Medium (CVSS 2.0 base score 5.0)
EPSS exploit prediction: 18% (97th percentile)
Actively exploited: Not listed in CISA KEV
Affected product: Microsoft Outlook Express
Published: 1999-05-11
Last modified: 2026-06-16

Description

Microsoft Outlook Express before 4.72.3612.1700 allows a malicious user to send a message that contains a .., which can inadvertently cause Outlook to re-enter POP3 command mode and cause the POP3 session to hang.

Frequently asked questions

What is CVE-1999-1033?: Microsoft Outlook Express before 4.72.3612.1700 allows a malicious user to send a message that contains a .., which can inadvertently cause Outlook to re-enter POP3 command mode and cause the POP3 session to hang.
How severe is CVE-1999-1033?: CVE-1999-1033 has a CVSS 2.0 base score of 5.0, rated medium severity.
Is CVE-1999-1033 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 18% (97th percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-1999-1033?: CVE-1999-1033 primarily affects Microsoft Outlook Express. In total, 3 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.
How do I fix CVE-1999-1033?: Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround.
When was CVE-1999-1033 published?: CVE-1999-1033 was published on 1999-05-11 and last updated on 2026-06-16.

References

Affected products (3)

cpe:2.3:a:microsoft:outlook_express:*:*:*:*:*:*:*:*
cpe:2.3:a:microsoft:outlook_express:4.27.3110.1:*:*:*:*:*:*:*
cpe:2.3:a:microsoft:outlook_express:4.72.3120.0:*:*:*:*:*:*:*

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