CVE-2019-1040

CVE-2019-1040 is a medium-severity vulnerability in Microsoft Windows 10 with a CVSS 3.x base score of 5.3. Its EPSS exploit-prediction score of 48% places it in the 99th percentile, indicating an elevated likelihood of exploitation.

Key facts

Description

A tampering vulnerability exists in Microsoft Windows when a man-in-the-middle attacker is able to successfully bypass the NTLM MIC (Message Integrity Check) protection. An attacker who successfully exploited this vulnerability could gain the ability to downgrade NTLM security features. To exploit this vulnerability, the attacker would need to tamper with the NTLM exchange. The attacker could then modify flags of the NTLM packet without invalidating the signature. The update addresses the vulnerability by hardening NTLM MIC protection on the server-side.

Frequently asked questions

What is CVE-2019-1040?
A tampering vulnerability exists in Microsoft Windows when a man-in-the-middle attacker is able to successfully bypass the NTLM MIC (Message Integrity Check) protection. An attacker who successfully exploited this vulnerability could gain the ability to downgrade NTLM security features. To exploit this vulnerability, the attacker would need to tamper with the NTLM exchange. The attacker could then modify flags of the NTLM packet without invalidating the signature. The update addresses the vulnerability by hardening NTLM MIC protection on the server-side.
How severe is CVE-2019-1040?
CVE-2019-1040 has a CVSS 3.x base score of 5.3, rated medium severity. It is exploitable over network with high attack complexity, requires no privileges and user interaction. Impact on confidentiality is none, integrity high, and availability none.
Is CVE-2019-1040 being actively exploited?
It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 48% (99th percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2019-1040?
CVE-2019-1040 primarily affects Microsoft Windows 10. In total, 19 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.
How do I fix CVE-2019-1040?
Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround.
When was CVE-2019-1040 published?
CVE-2019-1040 was published on 2019-06-12 and last updated on 2026-06-17.

References

Affected products (19)

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