What is CVE-2021-0421?

CVE-2021-0421 is a medium-severity vulnerability in Google Android, classified under Buffer Copy without Checking Size of Input (Classic Buffer Overflow). CVSS score: 5.5/10. Published 2021-09-27.

How severe is CVE-2021-0421?

Medium severity. CVSS v3 base score is 5.5 out of 10.

Buffer overflow in Google Android

CVE-2021-0421

In memory management driver, there is a possible information disclosure due to a missing bounds check. This could lead to local information disclosure with no additional execution privileges needed. User interaction is not needed for exploitation. Patch ID: ALPS05403499; Issue ID: ALPS05381235.

Vulnerability class: Buffer Overflow

Published 2021-09-27 · last modified 2026-06-17.

CVSS v3 metric

CVSS v3 base score 5.5 (Medium). Vector: CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:N.

EPSS exploit prediction

EPSS: 0.001 (1.4th percentile), scored 2026-09-30.

Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 1st percentile — 1.4% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.

EPSS over last 30 days · oldest: 0.001 · newest: 0.001 · change: 0.000

Affected products

Weakness classification (CWE)

CWE-120 — Buffer Copy without Checking Size of Input (Classic Buffer Overflow)

References

corp.mediatek.com/product-security-bulletin/September-2021 (Vendor Advisory)

Frequently asked questions

What is CVE-2021-0421?: CVE-2021-0421 is a medium-severity vulnerability in Google Android, classified under Buffer Copy without Checking Size of Input (Classic Buffer Overflow). CVSS score: 5.5/10. Published 2021-09-27.
How severe is CVE-2021-0421?: Medium severity. CVSS v3 base score is 5.5 out of 10.