CVE-2021-1771

Name: CVE-2021-1771
Creator: NVD / NIST
Published: 2021-04-02T18:15:20.7+00:00
License: https://creativecommons.org/publicdomain/zero/1.0/

LOWCVSS 3.3/10EPSS 0.55%

Last modified Jun 17, 2026

CVE-2021-1771 is a low-severity vulnerability rated 3.3/10 on the CVSS scale. This issue was addressed with improved checks. This issue is fixed in macOS Big Sur 11.2, Security Update 2021-001 Catalina, Security Update 2021-001 Mojave. EPSS estimates a 0.55% chance of exploitation in the next 30 days.

Description

This issue was addressed with improved checks. This issue is fixed in macOS Big Sur 11.2, Security Update 2021-001 Catalina, Security Update 2021-001 Mojave. A user that is removed from an iMessage group could rejoin the group.

Metrics

CVSS 3.1

3.3/10

CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:N/I:L/A:N

EPSS Probability

0.55%

41.6th percentile

Probability of exploitation in the next 30 days. Learn more

Affected Software

Vendor	Product	Versions
Apple	Mac Os X	>= 10.14, < 10.14.6
Apple	Mac Os X	>= 10.15, < 10.15.7
Apple	Mac Os X	10.14.6
Apple	Mac Os X	10.15.7
Apple	Macos	>= 11.0, < 11.2

References

https://support.apple.com/en-us/HT212147Release Notes, Vendor Advisory
https://support.apple.com/en-us/HT212147Release Notes, Vendor Advisory

Timeline

Published: Apr 2, 2021
Last Modified: Jun 17, 2026
Status: Modified

Frequently Asked Questions

What is CVE-2021-1771?

How severe is CVE-2021-1771?

CVE-2021-1771 has a CVSS score of 3.3/10 (LOW severity). The EPSS model estimates a 0.55% probability of exploitation in the next 30 days.

How do I fix CVE-2021-1771?

Check the vendor references and advisories linked above for patched versions and mitigation guidance. You can also run a Strix scan to test if your systems are affected.

Are you affected by CVE-2021-1771?

Run a free Strix scan to check your systems for this vulnerability.

Scan your code now

Source: NVD / NIST