What is CVE-2020-21547?

CVE-2020-21547 is a high-severity vulnerability in Saitoha Libsixel, classified under Out-of-bounds Write. CVSS score: 8.8/10. Published 2021-09-17.

How severe is CVE-2020-21547?

High severity. CVSS v3 base score is 8.8 out of 10.

Buffer overflow in Saitoha Libsixel

CVE-2020-21547

Libsixel 1.8.2 contains a heap-based buffer overflow in the dither_func_fs function in tosixel.c.

Vulnerability class: Buffer Overflow

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

CVSS v3 metric

CVSS v3 base score 8.8 (High). Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H.

EPSS exploit prediction

EPSS: 0.011 (64.1th percentile), scored 2026-10-20.

Low probability of exploitation in the next 30 days, but still tracked. 64th percentile — 64.1% 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

Saitoha Libsixel — versions 1.8.2

Weakness classification (CWE)

CWE-787 — Out-of-bounds Write

References

github.com/saitoha/libsixel/issues/114 (Exploit, Patch, Third Party Advisory, Issue Tracking)

Frequently asked questions

What is CVE-2020-21547?: CVE-2020-21547 is a high-severity vulnerability in Saitoha Libsixel, classified under Out-of-bounds Write. CVSS score: 8.8/10. Published 2021-09-17.
How severe is CVE-2020-21547?: High severity. CVSS v3 base score is 8.8 out of 10.