CVE-2019-20398Public exploitNetwork attack vector

Application crash via copied unresolved extensions

Published Jan 22, 2020 · Updated Aug 5, 2024

NULL pointer dereference in CESNET libyang before 1.0-r3 allows attackers to crash applications via a crafted YANG file. lys_restr_dup() copies unresolved grouping-restriction extensions, leaving lys_extension_instances_free() to dereference a NULL extension pointer. A user or consuming service must cause the application to parse attacker-controlled YANG input; the documented consequence is a process crash, not data disclosure or code execution.

CVSS severity6.5
Medium
EPSS probability1.82%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
Coverage for this vulnerability

See if you're affected

Explore vulnerability checks for your environment with Hinoki.

Book a demo

Summary

What happened

NULL pointer dereference in CESNET libyang before 1.0-r3 allows attackers to crash applications via a crafted YANG file. lys_restr_dup() copies unresolved grouping-restriction extensions, leaving lys_extension_instances_free() to dereference a NULL extension pointer. A user or consuming service must cause the application to parse attacker-controlled YANG input; the documented consequence is a process crash, not data disclosure or code execution.

The record

CVE
CVE-2019-20398
Published
Jan 22, 2020
Updated
Aug 5, 2024
Vendor
Unknown vendor
Product
Unknown product
Classifications
CWE-476, T1499
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Jan 22, 2020CVE publishedPublication date reported by the CVE source.
  2. Aug 5, 2024Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

Compare your product and version with the public record. A matching version still requires validation against your environment.

Is a vulnerable build present?

Affected buildAffected product and version details are unavailable.

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Affected products and versions are unavailable in this record.

Published CVSS scores

6.5NIST NVDCVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:N/A:H
4.3NIST NVDAV:N/AC:M/Au:N/C:N/I:N/A:P

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

No observations available

Sep 9, 2026Sep 15, 2026
Latest reporting daySep 15, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitPublished

Weakness, pattern, technique

CWE-476NULL Pointer Dereference
T1499Endpoint Denial of Service

Public exploit references

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

See the directory against your own environment.

Your stack

Check the software in your environment

Book a demo to see how Hinoki identifies affected software and validates exploitability in your environment.

Book a demo