What is CVE-2019-20395?

CVE-2019-20395 is a medium-severity vulnerability in Cesnet Libyang, classified under Uncontrolled Recursion. CVSS score: 6.5/10. Published 2020-01-22.

How severe is CVE-2019-20395?

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

Vulnerability in Cesnet Libyang

CVE-2019-20395

A stack consumption issue is present in libyang before v1.0-r1 due to the self-referential union type containing leafrefs. Applications that use libyang to parse untrusted input yang files may crash.

Published 2020-01-22 · 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: 0.019 (78.3th percentile), scored 2026-09-29.

Low probability of exploitation in the next 30 days, but still tracked. 78th percentile — 78.3% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.

EPSS over last 30 days · oldest: 0.018 · newest: 0.019 · change: +0.000

Affected products

Cesnet Libyang — versions 0.11, 0.12, 0.13

Weakness classification (CWE)

CWE-674 — Uncontrolled Recursion

References

github.com/CESNET/libyang/compare/v0.16-r3...v1.0-r1 (Third Party Advisory)
github.com/CESNET/libyang/issues/724 (Exploit, Third Party Advisory)
github.com/CESNET/libyang/commit/4e610ccd87a2ba9413819777d508f71163fcc237 (Third Party Advisory)
bugzilla.redhat.com/show_bug.cgi (Third Party Advisory, Issue Tracking)
lists.debian.org/debian-lts-announce/2023/09/msg00019.html (mailing-list)

Frequently asked questions

What is CVE-2019-20395?: CVE-2019-20395 is a medium-severity vulnerability in Cesnet Libyang, classified under Uncontrolled Recursion. CVSS score: 6.5/10. Published 2020-01-22.
How severe is CVE-2019-20395?: Medium severity. CVSS v3 base score is 6.5 out of 10.