How severe is CVE-2021-30977?

CVE-2021-30977 has a CVSS 3.x base score of 7.8, rated high severity. It is exploitable over local access with low attack complexity, requires no privileges and user interaction. Impact on confidentiality is high, integrity high, and availability high.

Is CVE-2021-30977 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 2% (71st percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2021-30977?

CVE-2021-30977 primarily affects Apple Mac Os X. In total, 12 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.

How do I fix CVE-2021-30977?

Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its high severity, prioritise patching exposed systems.

When was CVE-2021-30977 published?

CVE-2021-30977 was published on 2021-08-24 and last updated on 2026-06-17.

CVE-2021-30977

CVE-2021-30977 is a high-severity vulnerability in Apple Mac Os X with a CVSS 3.x base score of 7.8. It is not currently listed as actively exploited by CISA, and its EPSS exploit-prediction score is low. The underlying weakness is classified as CWE-120.

Key facts

Severity: High (CVSS 3.x base score 7.8)
CVSS v2: 9.3
EPSS exploit prediction: 2% (71st percentile)
Actively exploited: Not listed in CISA KEV
Weakness: CWE-120
Affected product: Apple Mac Os X
Published: 2021-08-24
Last modified: 2026-06-17

Description

A buffer overflow was addressed with improved bounds checking. This issue is fixed in macOS Monterey 12.1, Security Update 2021-008 Catalina, macOS Big Sur 11.6.2. A malicious application may be able to execute arbitrary code with kernel privileges.

Frequently asked questions

What is CVE-2021-30977?: A buffer overflow was addressed with improved bounds checking. This issue is fixed in macOS Monterey 12.1, Security Update 2021-008 Catalina, macOS Big Sur 11.6.2. A malicious application may be able to execute arbitrary code with kernel privileges.
How severe is CVE-2021-30977?: CVE-2021-30977 has a CVSS 3.x base score of 7.8, rated high severity. It is exploitable over local access with low attack complexity, requires no privileges and user interaction. Impact on confidentiality is high, integrity high, and availability high.
Is CVE-2021-30977 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 2% (71st percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2021-30977?: CVE-2021-30977 primarily affects Apple Mac Os X. In total, 12 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.
How do I fix CVE-2021-30977?: Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its high severity, prioritise patching exposed systems.
When was CVE-2021-30977 published?: CVE-2021-30977 was published on 2021-08-24 and last updated on 2026-06-17.

References

Affected products (12)

cpe:2.3:o:apple:mac_os_x:*:*:*:*:*:*:*:*
cpe:2.3:o:apple:mac_os_x:10.15.7:-:*:*:*:*:*:*
cpe:2.3:o:apple:mac_os_x:10.15.7:security_update_2020-001:*:*:*:*:*:*
cpe:2.3:o:apple:mac_os_x:10.15.7:security_update_2021-001:*:*:*:*:*:*
cpe:2.3:o:apple:mac_os_x:10.15.7:security_update_2021-002:*:*:*:*:*:*
cpe:2.3:o:apple:mac_os_x:10.15.7:security_update_2021-003:*:*:*:*:*:*
cpe:2.3:o:apple:mac_os_x:10.15.7:security_update_2021-004:*:*:*:*:*:*
cpe:2.3:o:apple:mac_os_x:10.15.7:security_update_2021-005:*:*:*:*:*:*
cpe:2.3:o:apple:mac_os_x:10.15.7:security_update_2021-006:*:*:*:*:*:*
cpe:2.3:o:apple:mac_os_x:10.15.7:security_update_2021-007:*:*:*:*:*:*
cpe:2.3:o:apple:mac_os_x:10.15.7:supplemental_update:*:*:*:*:*:*
cpe:2.3:o:apple:macos:*:*:*:*:*:*:*:*

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