What is CVE-2021-0561?

CVE-2021-0561 is a medium-severity vulnerability in Google Android, classified under Out-of-bounds Write. CVSS score: 5.5/10. Published 2021-06-22.

How severe is CVE-2021-0561?

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

Is CVE-2021-0561 known to be exploited?

1 public proof-of-concept repositories are indexed. Not currently listed in the CISA KEV catalog.

Buffer overflow in Google Android

CVE-2021-0561

In append_to_verify_fifo_interleaved_ of stream_encoder.c, there is a possible out of bounds write 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.Product: AndroidVersions: Android-11Android ID: A-174302683

Vulnerability class: Buffer Overflow

Published 2021-06-22 · 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: 0.005 (37.9th percentile), scored 2026-10-02.

Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 38th percentile — 37.9% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.

EPSS over last 30 days · oldest: 0.005 · newest: 0.005 · change: 0.000

Affected products

Google Android — versions 11.0
Debian Linux — versions 9.0, 10.0
Fedoraproject Fedora — versions 35, 36
Android — versions Android-11

Weakness classification (CWE)

CWE-787 — Out-of-bounds Write

Public proof-of-concept exploits

ARPSyndicate/cvemon

References

source.android.com/security/bulletin/pixel/2021-06-01 (Patch, Vendor Advisory)
lists.fedoraproject.org/archives/list/package-announce@lists.fedoraproject.org/… (vendor-advisory)
lists.debian.org/debian-lts-announce/2022/03/msg00022.html (mailing-list, Mailing List, Third Party Advisory)
lists.fedoraproject.org/archives/list/package-announce@lists.fedoraproject.org/… (vendor-advisory)
lists.debian.org/debian-lts-announce/2022/09/msg00003.html (mailing-list, Mailing List, Third Party Advisory)

Frequently asked questions

What is CVE-2021-0561?: CVE-2021-0561 is a medium-severity vulnerability in Google Android, classified under Out-of-bounds Write. CVSS score: 5.5/10. Published 2021-06-22.
How severe is CVE-2021-0561?: Medium severity. CVSS v3 base score is 5.5 out of 10.
Is CVE-2021-0561 known to be exploited?: 1 public proof-of-concept repositories are indexed. Not currently listed in the CISA KEV catalog.