CVE-2021-39517: Jpeg Libjpeg

Medium severity, CVSS 6.5. EPSS: 0.9% chance of exploitation in the next 30 days.

An issue was discovered in libjpeg through 2020021. A NULL pointer dereference exists in the function BlockBitmapRequester::ReconstructUnsampled() located in blockbitmaprequester.cpp. It allows an attacker to cause Denial of Service.

Affected products

• Jpeg Libjpeg: up to and including 2020021

Published 2021-09-20. Last modified 2026-06-17.