CVE-2021-39921: Debian Linux

High severity, CVSS 7.5. EPSS: 3.4% chance of exploitation in the next 30 days.

NULL pointer exception in the Modbus dissector in Wireshark 3.4.0 to 3.4.9 and 3.2.0 to 3.2.17 allows denial of service via packet injection or crafted capture file

Affected products

• Debian Debian Linux: version 9.0 only
• Fedoraproject Fedora: version 34 only; version 35 only
• Wireshark Wireshark: from 3.2.0, up to and including 3.2.17; from 3.4.0, up to and including 3.4.9

Published 2021-11-19. Last modified 2026-06-17.