How severe is CVE-2021-1771?

CVE-2021-1771 has a CVSS 3.x base score of 3.3, rated low severity. It is exploitable over local access with low attack complexity, requires no privileges and user interaction. Impact on confidentiality is none, integrity low, and availability none.

Is CVE-2021-1771 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 1% (42nd percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2021-1771?

CVE-2021-1771 primarily affects Apple Mac Os X. In total, 16 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.

How do I fix CVE-2021-1771?

Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround.

When was CVE-2021-1771 published?

CVE-2021-1771 was published on 2021-04-02 and last updated on 2026-06-17.

CVE-2021-1771

CVE-2021-1771 is a low-severity vulnerability in Apple Mac Os X with a CVSS 3.x base score of 3.3. It is not currently listed as actively exploited by CISA, and its EPSS exploit-prediction score is low.

Key facts

Severity: Low (CVSS 3.x base score 3.3)
CVSS v2: 4.3
EPSS exploit prediction: 1% (42nd percentile)
Actively exploited: Not listed in CISA KEV
Affected product: Apple Mac Os X
Published: 2021-04-02
Last modified: 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.

Frequently asked questions

What is CVE-2021-1771?: 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.
How severe is CVE-2021-1771?: CVE-2021-1771 has a CVSS 3.x base score of 3.3, rated low severity. It is exploitable over local access with low attack complexity, requires no privileges and user interaction. Impact on confidentiality is none, integrity low, and availability none.
Is CVE-2021-1771 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 1% (42nd percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2021-1771?: CVE-2021-1771 primarily affects Apple Mac Os X. In total, 16 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.
How do I fix CVE-2021-1771?: Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround.
When was CVE-2021-1771 published?: CVE-2021-1771 was published on 2021-04-02 and last updated on 2026-06-17.

References

https://support.apple.com/en-us/HT212147

Affected products (16)

cpe:2.3:o:apple:mac_os_x:*:*:*:*:*:*:*:*
cpe:2.3:o:apple:mac_os_x:10.14.6:-:*:*:*:*:*:*
cpe:2.3:o:apple:mac_os_x:10.14.6:security_update_2019-001:*:*:*:*:*:*
cpe:2.3:o:apple:mac_os_x:10.14.6:security_update_2019-002:*:*:*:*:*:*
cpe:2.3:o:apple:mac_os_x:10.14.6:security_update_2020-001:*:*:*:*:*:*
cpe:2.3:o:apple:mac_os_x:10.14.6:security_update_2020-002:*:*:*:*:*:*
cpe:2.3:o:apple:mac_os_x:10.14.6:security_update_2020-003:*:*:*:*:*:*
cpe:2.3:o:apple:mac_os_x:10.14.6:security_update_2020-004:*:*:*:*:*:*
cpe:2.3:o:apple:mac_os_x:10.14.6:security_update_2020-005:*:*:*:*:*:*
cpe:2.3:o:apple:mac_os_x:10.14.6:security_update_2020-006:*:*:*:*:*:*
cpe:2.3:o:apple:mac_os_x:10.14.6:security_update_2020-007:*:*:*:*:*:*
cpe:2.3:o:apple:mac_os_x:10.14.6:supplemental_update:*:*:*:*:*:*
cpe:2.3:o:apple:mac_os_x:10.14.6:supplemental_update_2:*:*:*:*:*:*
cpe:2.3:o:apple:mac_os_x:10.15.7:-:*:*:*:*:*:*
cpe:2.3:o:apple:mac_os_x:10.15.7:supplemental_update:*:*:*:*:*:*
cpe:2.3:o:apple:macos:*:*:*:*:*:*:*:*

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