CVE-2021-1771

Severity: low (CVSS 3.3 v3.1)
Exploited in the wild: not listed in CISA KEV
EPSS: 0.6% probability of exploitation in the next 30 days
Public exploit or detection template: none known
Published: 2021-04-02 · updated 2026-06-17

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.

Affected products

macOS: from 10.14 before 10.14.6; from 10.15 before 10.15.7; 10.14.6, 10.14.6-security_update_2019-001, 10.14.6-security_update_2019-002, 10.14.6-security_update_2020-001, 10.14.6-security_update_2020-002, 10.14.6-security_update_2020-003 (+8) — fixed in 10.14.6, 10.15.7
Apple macOS: from 11.0 before 11.2 — fixed in 11.2

How to fix

Upgrade to a fixed version: macOS 10.14.6, 10.15.7; Apple macOS 11.2. Check the vendor advisory for mitigations.

References

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