What is CVE-2020-21603?

CVE-2020-21603 is a medium-severity vulnerability in Struktur Libde265, classified under Out-of-bounds Write. CVSS score: 6.5/10. Published 2021-09-16.

How severe is CVE-2020-21603?

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

Is CVE-2020-21603 known to be exploited?

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

Buffer overflow in Struktur Libde265

CVE-2020-21603

libde265 v1.0.4 contains a heap buffer overflow in the put_qpel_0_0_fallback_16 function, which can be exploited via a crafted a file.

Vulnerability class: Buffer Overflow

Published 2021-09-16 · 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:N/I:N/A:H.

EPSS exploit prediction

EPSS: 0.011 (63.2th percentile), scored 2026-10-02.

Low probability of exploitation in the next 30 days, but still tracked. 63rd percentile — 63.2% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.

EPSS over last 30 days · oldest: 0.011 · newest: 0.011 · change: 0.000

Affected products

Struktur Libde265 — versions 1.0.4

Weakness classification (CWE)

CWE-787 — Out-of-bounds Write

Public proof-of-concept exploits

Live-Hack-CVE/CVE-2020-21603

References

github.com/strukturag/libde265/issues/240 (Exploit, Third Party Advisory, Issue Tracking)
www.debian.org/security/2023/dsa-5346 (vendor-advisory)

Frequently asked questions

What is CVE-2020-21603?: CVE-2020-21603 is a medium-severity vulnerability in Struktur Libde265, classified under Out-of-bounds Write. CVSS score: 6.5/10. Published 2021-09-16.
How severe is CVE-2020-21603?: Medium severity. CVSS v3 base score is 6.5 out of 10.
Is CVE-2020-21603 known to be exploited?: 1 public proof-of-concept repositories are indexed. Not currently listed in the CISA KEV catalog.