CVE-2019-20398

Severity: medium (CVSS 6.5 v3.1)
Exploited in the wild: not listed in CISA KEV
EPSS: 1.8% probability of exploitation in the next 30 days
Public exploit or detection template: yes
Published: 2020-01-22 · updated 2026-06-17
Weakness: CWE-476

Description

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: 0.11-r1, 0.11-r2, 0.12-r1, 0.12-r2, 0.13-r1, 0.13-r2 (+7)

References

https://bugzilla.redhat.com/show_bug.cgi?id=1793935
https://github.com/CESNET/libyang/commit/7852b272ef77f8098c35deea6c6f09cb78176f08
https://github.com/CESNET/libyang/compare/v1.0-r2...v1.0-r3
https://github.com/CESNET/libyang/issues/773
https://lists.debian.org/debian-lts-announce/2023/09/msg00019.html
https://bugzilla.redhat.com/show_bug.cgi?id=1793935
https://github.com/CESNET/libyang/commit/7852b272ef77f8098c35deea6c6f09cb78176f08
https://github.com/CESNET/libyang/compare/v1.0-r2...v1.0-r3
https://github.com/CESNET/libyang/issues/773
https://lists.debian.org/debian-lts-announce/2023/09/msg00019.html

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