CVE-2019-20398: Cesnet Libyang

Medium severity, CVSS 6.5. EPSS: 1.8% chance of exploitation in the next 30 days.

A NULL pointer dereference is present in libyang before v1.0-r3 in the function lys_extension_instances_free() due to a copy of unresolved extensions in lys_restr_dup(). Applications that use libyang to parse untrusted input yang files may crash.

Affected products

• Cesnet Libyang: version 0.11 only; version 0.12 only; version 0.13 only; version 0.14 only; version 0.15 only; version 0.16 only; …

Published 2020-01-22. Last modified 2026-06-17.