CVE-2019-20398

Exp

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.

Published: 2020-01-22 Last update: 2024-11-21 Assigner: [email protected] Source: [email protected]
NVD Status：Modified，CVE State: published
View at NVD, CVE.org, EUVD

CVE-2019-20398 is rated High Exploit Risk (69.2/100): CVSS Medium severity, with medium exploitation likelihood (EPSS 1.82%). 1 public exploit reference(s) are indexed (Exploit-DB). EPSS rose +1.61% over the last day, indicating growing attacker interest. Public exploits are available—assess exposure, apply mitigations, and prioritize patching.

Risk is dynamic; we continuously reassess and refresh what is shown on this page as upstream context changes.

Public exploit references (Exploit-DB) for CVE-2019-20398

EDB-ID Source Kind Published Link
— nvd_ref exploit_tag Exploit-DB ↗

Exploit prediction scoring system (EPSS) score for CVE-2019-20398

EPSS lead: Daily EPSS estimates relative likelihood of exploitation; percentile ranks this CVE among scored vulnerabilities (higher = more severe relative rank).

# Date Old EPSS score New EPSS score Delta (New - Old)
1 2026-06-15 0.21% 1.82% +1.61%
2 2025-11-21 0.41% 0.21% -0.21%
3 2025-11-18 — 0.41% —

Full EPSS history (14 records total)

Common vulnerability scoring system (CVSS) metrics for CVE-2019-20398

CVSS metrics for this CVE.

Base score Version Severity Vector Exploitability Impact Score source
6.5 3.1 MEDIUM
CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:N/A:H Click to expand
Attack vector (AV:N)
Could be attacked over the internet or any normal routed network—not just someone sitting at the machine.
Attack complexity (AC:L)
Once they can reach the bug, pulling it off is straightforward—no weird race conditions or rare setup.
Privileges required (PR:N)
No account or special rights needed—anonymous or random user is enough.
User interaction (UI:R)
A real person has to do something—click, install, enable—otherwise it doesn’t land.
Scope (S:U)
Damage stays in the same “trust bubble” as the broken component—no big spill into unrelated systems.
Confidentiality (C:N)
Doesn’t really leak secrets in a meaningful way.
Integrity (I:N)
Data isn’t meaningfully altered or forged.
Availability (A:H)
Could take the service down hard or make it unusable for people who depend on it.
 2.8 3.6 [email protected]
4.3 2.0 MEDIUM
AV:N/AC:M/Au:N/C:N/I:N/A:P Click to expand
Access vector (AV:N)
Can be exploited remotely over network reachability.
Access complexity (AC:M)
Exploitation needs some favorable conditions, but not exceptional ones.
Authentication (AU:N)
No authentication is required.
Confidentiality impact (C:N)
No confidentiality impact.
Integrity impact (I:N)
No integrity impact.
Availability impact (A:P)
Partial availability impact.
 8.6 2.9 [email protected]

Weakness enumeration for CVE-2019-20398

OS Trackers for CVE-2019-20398

vendor priority summary link
debian not yet assigned CVE-2019-20398 not yet assigned priority: Debian including 1 source packages (libyang), 4 status rows across 4 suites (bullseye, forky, sid, trixie): resolved 4. https://security-tracker.debian.org/tracker/CVE-2019-20398
redhat low — https://access.redhat.com/security/cve/CVE-2019-20398
ubuntu medium CVE-2019-20398 medium priority: Ubuntu including 1 source packages (libyang), 17 status rows across 17 suites (bionic, eoan, focal, groovy, hirsute, impish, jammy, kinetic, lunar, mantic, noble, oracular, plucky, questing, trusty, upstream, xenial): DNE 7, not-affected 5, ignored 3, needed 1, released 1. https://ubuntu.com/security/CVE-2019-20398

Affected software / configurations for CVE-2019-20398

Vendor Product Version Raw CPE
cesnet libyang 0.11 cpe:2.3:a:cesnet:libyang:0.11:r1:*:*:*:*:*:*
cesnet libyang 0.11 cpe:2.3:a:cesnet:libyang:0.11:r2:*:*:*:*:*:*
cesnet libyang 0.12 cpe:2.3:a:cesnet:libyang:0.12:r1:*:*:*:*:*:*
cesnet libyang 0.12 cpe:2.3:a:cesnet:libyang:0.12:r2:*:*:*:*:*:*
cesnet libyang 0.13 cpe:2.3:a:cesnet:libyang:0.13:r1:*:*:*:*:*:*
cesnet libyang 0.13 cpe:2.3:a:cesnet:libyang:0.13:r2:*:*:*:*:*:*
cesnet libyang 0.14 cpe:2.3:a:cesnet:libyang:0.14:r1:*:*:*:*:*:*
cesnet libyang 0.15 cpe:2.3:a:cesnet:libyang:0.15:r1:*:*:*:*:*:*
cesnet libyang 0.16 cpe:2.3:a:cesnet:libyang:0.16:r1:*:*:*:*:*:*
cesnet libyang 0.16 cpe:2.3:a:cesnet:libyang:0.16:r2:*:*:*:*:*:*
cesnet libyang 0.16 cpe:2.3:a:cesnet:libyang:0.16:r3:*:*:*:*:*:*
cesnet libyang 1.0 cpe:2.3:a:cesnet:libyang:1.0:r1:*:*:*:*:*:*
cesnet libyang 1.0 cpe:2.3:a:cesnet:libyang:1.0:r2:*:*:*:*:*:*

References for CVE-2019-20398

cvelogic Threat Intelligence