CVE-2021-1730

Microsoft Exchange Server Spoofing Vulnerability

Description

A spoofing vulnerability exists in Microsoft Exchange Server which could result in an attack that would allow a malicious actor to impersonate the user. This update addresses this vulnerability. To prevent these types of attacks, Microsoft recommends customers to download inline images from different DNSdomains than the rest of OWA. Please see further instructions in the FAQ to put in place this mitigations.

5.4

CVSS

Severity: Medium

CVSS 3.1 •

CVSS 2.0 •

EPSS 3.28% Top 15%

Vendor Advisory microsoft.com

Affected: Microsoft Microsoft Exchange Server 2019 Cumulative Update 7

Affected: Microsoft Microsoft Exchange Server 2016 Cumulative Update 18

References

Link	Tags
https://portal.msrc.microsoft.com/en-US/security-guidance/advisory/CVE-2021-1730	patch vendor advisory

Frequently Asked Questions

What is the severity of CVE-2021-1730?: CVE-2021-1730 has been scored as a medium severity vulnerability.
How to fix CVE-2021-1730?: To fix CVE-2021-1730, make sure you are using an up-to-date version of the affected component(s) by checking the vendor release notes. As for now, there are no other specific guidelines available.
Is CVE-2021-1730 being actively exploited in the wild?: It is possible that CVE-2021-1730 is being exploited or will be exploited in a near future based on public information. According to its EPSS score, there is a ~3% probability that this vulnerability will be exploited by malicious actors in the next 30 days.
What software or system is affected by CVE-2021-1730?: CVE-2021-1730 affects Microsoft Microsoft Exchange Server 2019 Cumulative Update 7, Microsoft Microsoft Exchange Server 2016 Cumulative Update 18.

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