CVE-2021-31207KEV · OVERDUE

Microsoft Exchange Server Security Feature Bypass Vulnerability

Medium · published May 11, 2021

Patch now

The score understates this — it's already being exploited

CVSS calls it medium at 6.6. It is confirmed in active exploitation. It sits in the 100.0th percentile for exploit probability.

1754
days past CISA
deadline
CVSS v3.1
6.6
EPSS
100%
Percentile
100.0
In the wild
Confirmed
What it is

⚠️ A clever workaround easily bypasses security checks in Microsoft Exchange Server! Attackers can navigate around protections like it's a walk in the park. 🔥 Think of it like a restaurant with a hidden service entrance that skips the usual checks. A crafty diner could sneak in without so much as a glance from the bouncer! If exploited, this vulnerability can allow unauthorized access to sensitive email data, potentially leading to data breaches or system compromises. This opens the door for attackers to manipulate email communications or access confidential information.

Put simply

Think of it like a restaurant with a hidden service entrance that skips the usual checks. A crafty diner could sneak in without so much as a glance from the bouncer! This vulnerability exists due to improper validation of security features in Microsoft Exchange Server, allowing potential bypass of security protocols.

What to do

If exploited, this vulnerability can allow unauthorized access to sensitive email data, potentially leading to data breaches or system compromises. This opens the door for attackers to manipulate email communications or access confidential information. To mitigate this vulnerability, ensure you're on the latest version of Microsoft Exchange Server. Review your security configurations and apply all relevant patches promptly to safeguard your systems. You've got this! By following these steps, you're one step closer to securing your email fortress! 🛡️

The record
Technical detail
CVSS v3.1
6.6 · MEDIUM
Vector
CVSS:3.1/AV:N/AC:H/PR:H/UI:N/S:U/C:H/I:H/A:H/E:U/RL:O/RC:C
CVSS v4.0
Not supplied
EPSS
0.99782 · 100.0th percentile
Published
2021-05-11T19:11Z
KEV added
2021-11-03 · due 2021-11-17
EPSS history
Timeline
  • 03 NOV 00:00Z
    Added to CISA KEV — remediate by Nov 17
    kev
  • 11 MAY 19:11Z
    Microsoft Exchange Server Security Feature Bypass Vulnerability
    cvelistv5