What is CVE-2021-30755?

CVE-2021-30755 is a medium-severity vulnerability in Apple macOS, classified under Out-of-bounds Read. CVSS score: 6.5/10. Published 2021-09-08.

How severe is CVE-2021-30755?

Medium severity. CVSS v3 base score is 6.5 out of 10.

Out-of-bounds Read in Apple macOS

CVE-2021-30755

Processing a maliciously crafted font may result in the disclosure of process memory. This issue is fixed in macOS Big Sur 11.4, tvOS 14.6, watchOS 7.5. An out-of-bounds read was addressed with improved input validation.

Vulnerability class: Buffer Overflow

Published 2021-09-08 · last modified 2026-06-17.

CVSS v3 metric

CVSS v3 base score 6.5 (Medium). Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:N/A:N.

EPSS exploit prediction

EPSS: 0.013 (70.0th percentile), scored 2026-10-02.

Low probability of exploitation in the next 30 days, but still tracked. 70th percentile — 70.0% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.

EPSS over last 30 days · oldest: 0.013 · newest: 0.013 · change: 0.000

Affected products

Apple macOS — versions unspecified
Apple tvOS
Apple watchOS

Weakness classification (CWE)

CWE-125 — Out-of-bounds Read

References

support.apple.com/en-us/HT212529 (Vendor Advisory)
support.apple.com/en-us/HT212532 (Vendor Advisory)
support.apple.com/en-us/HT212533 (Vendor Advisory)

Frequently asked questions

What is CVE-2021-30755?: CVE-2021-30755 is a medium-severity vulnerability in Apple macOS, classified under Out-of-bounds Read. CVSS score: 6.5/10. Published 2021-09-08.
How severe is CVE-2021-30755?: Medium severity. CVSS v3 base score is 6.5 out of 10.