How severe is CVE-2019-20397?

CVE-2019-20397 has a CVSS 3.x base score of 8.8, rated high severity. It is exploitable over network with low attack complexity, requires no privileges and user interaction. Impact on confidentiality is high, integrity high, and availability high.

Is CVE-2019-20397 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 2% (83rd percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2019-20397?

CVE-2019-20397 primarily affects Cesnet Libyang. In total, 11 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.

How do I fix CVE-2019-20397?

Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its high severity, prioritise patching exposed systems.

When was CVE-2019-20397 published?

CVE-2019-20397 was published on 2020-01-22 and last updated on 2026-06-17.

CVE-2019-20397

CVE-2019-20397 is a high-severity vulnerability in Cesnet Libyang with a CVSS 3.x base score of 8.8. It is not currently listed as actively exploited by CISA, and its EPSS exploit-prediction score is low. The underlying weakness is classified as CWE-415.

Key facts

Severity: High (CVSS 3.x base score 8.8)
CVSS v2: 6.8
EPSS exploit prediction: 2% (83rd percentile)
Actively exploited: Not listed in CISA KEV
Weakness: CWE-415
Affected product: Cesnet Libyang
Published: 2020-01-22
Last modified: 2026-06-17

Description

A double-free is present in libyang before v1.0-r1 in the function yyparse() when an organization field is not terminated. Applications that use libyang to parse untrusted input yang files may be vulnerable to this flaw, which would cause a crash or potentially code execution.

Frequently asked questions

What is CVE-2019-20397?: A double-free is present in libyang before v1.0-r1 in the function yyparse() when an organization field is not terminated. Applications that use libyang to parse untrusted input yang files may be vulnerable to this flaw, which would cause a crash or potentially code execution.
How severe is CVE-2019-20397?: CVE-2019-20397 has a CVSS 3.x base score of 8.8, rated high severity. It is exploitable over network with low attack complexity, requires no privileges and user interaction. Impact on confidentiality is high, integrity high, and availability high.
Is CVE-2019-20397 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 2% (83rd percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2019-20397?: CVE-2019-20397 primarily affects Cesnet Libyang. In total, 11 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.
How do I fix CVE-2019-20397?: Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its high severity, prioritise patching exposed systems.
When was CVE-2019-20397 published?: CVE-2019-20397 was published on 2020-01-22 and last updated on 2026-06-17.

References

Affected products (11)

cpe:2.3:a:cesnet:libyang:0.11:r1:*:*:*:*:*:*
cpe:2.3:a:cesnet:libyang:0.11:r2:*:*:*:*:*:*
cpe:2.3:a:cesnet:libyang:0.12:r1:*:*:*:*:*:*
cpe:2.3:a:cesnet:libyang:0.12:r2:*:*:*:*:*:*
cpe:2.3:a:cesnet:libyang:0.13:r1:*:*:*:*:*:*
cpe:2.3:a:cesnet:libyang:0.13:r2:*:*:*:*:*:*
cpe:2.3:a:cesnet:libyang:0.14:r1:*:*:*:*:*:*
cpe:2.3:a:cesnet:libyang:0.15:r1:*:*:*:*:*:*
cpe:2.3:a:cesnet:libyang:0.16:r1:*:*:*:*:*:*
cpe:2.3:a:cesnet:libyang:0.16:r2:*:*:*:*:*:*
cpe:2.3:a:cesnet:libyang:0.16:r3:*:*:*:*:*:*

More vulnerabilities in Cesnet Libyang

CVE-2019-19334 — Critical (CVSS 9.8): In all versions of libyang before 1.0-r5, a stack-based buffer overflow was discovered in the way libyang parses YANG…
CVE-2019-19333 — Critical (CVSS 9.8): In all versions of libyang before 1.0-r5, a stack-based buffer overflow was discovered in the way libyang parses YANG…
CVE-2019-20394 — High (CVSS 8.8): A double-free is present in libyang before v1.0-r3 in the function yyparse() when a type statement in used in a…
CVE-2019-20393 — High (CVSS 8.8): A double-free is present in libyang before v1.0-r1 in the function yyparse() when an empty description is used.…
CVE-2023-26917 — High (CVSS 7.5): libyang from v2.0.164 to v2.1.30 was discovered to contain a NULL pointer dereference via the function…
CVE-2021-28906 — High (CVSS 7.5): In function read_yin_leaf() in libyang <= v1.0.225, it doesn't check whether the value of retval->ext[r] is NULL. In…

All CVEs affecting Cesnet Libyang →

Other CWE-415 (Double Free) vulnerabilities

CVE-2018-0101 — Critical (CVSS 10.0): A vulnerability in the Secure Sockets Layer (SSL) VPN functionality of the Cisco Adaptive Security Appliance (ASA)…
CVE-2026-8925 — Critical (CVSS 9.8): The curl logic that works with SASL authentication could end up cleaning up the GSASL context *twice* without clearing…
CVE-2020-37239 — Critical (CVSS 9.8): libbabl 0.1.62 contains a broken double free detection vulnerability that allows attackers to bypass memory safety…
CVE-2026-43011 — Critical (CVSS 9.8): In the Linux kernel, the following vulnerability has been resolved: net/x25: Fix potential double free of skb When…
CVE-2026-31609 — Critical (CVSS 9.8): In the Linux kernel, the following vulnerability has been resolved: smb: client: avoid double-free in…
CVE-2026-31608 — Critical (CVSS 9.8): In the Linux kernel, the following vulnerability has been resolved: smb: server: avoid double-free in…

Browse all CWE-415 (Double Free) vulnerabilities →