What is CVE-2021-45340?

CVE-2021-45340 is a medium-severity vulnerability in Libsixel, classified under NULL Pointer Dereference. CVSS score: 6.5/10. Published 2022-01-25.

How severe is CVE-2021-45340?

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

NULL pointer dereference in Libsixel

CVE-2021-45340

In Libsixel prior to and including v1.10.3, a NULL pointer dereference in the stb_image.h component of libsixel allows attackers to cause a denial of service (DOS) via a crafted PICT file.

Published 2022-01-25 · 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: 0.009 (58.9th percentile), scored 2026-10-01.

Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 59th percentile — 58.9% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.

EPSS over last 30 days · oldest: 0.009 · newest: 0.009 · change: 0.000

Affected products

Libsixel

Weakness classification (CWE)

CWE-476 — NULL Pointer Dereference

References

github.com/libsixel/libsixel/issues/51 (Exploit, Patch, Third Party Advisory, Issue Tracking)

Frequently asked questions

What is CVE-2021-45340?: CVE-2021-45340 is a medium-severity vulnerability in Libsixel, classified under NULL Pointer Dereference. CVSS score: 6.5/10. Published 2022-01-25.
How severe is CVE-2021-45340?: Medium severity. CVSS v3 base score is 6.5 out of 10.