Security readout for executives and security teams
Plain-English summary
libyang can overflow stack memory when parsing a specially crafted YANG file using an identityref leaf. Organizations are mainly exposed if software accepts YANG models from untrusted sources. The likely business impact is service disruption, with possible code execution noted by the CVE source.
Executive priority
Treat as a high-priority patch for systems that process external YANG models. Prioritize internet-facing or automation-facing management platforms first. Defer only where libyang is absent or strictly isolated from untrusted input.
Technical view
CVE-2019-19334 is a CWE-121 stack-based buffer overflow in libyang before 1.0-r5 during parsing of identityref leaf types in YANG files. CVSS 3.0 is 8.1 high, with network attack vector, high complexity, no privileges, and no user interaction.
Likely exposure
Exposure is most likely in network management, configuration, or automation software that links libyang and parses user-supplied or externally obtained YANG files. Systems using libyang only for trusted local models have lower practical exposure.
Exploitation context
The provided sources do not show CISA KEV listing or active exploitation. Exploitation requires a vulnerable libyang version and an application path that parses untrusted YANG content containing the affected identityref construct.
Researcher notes
The strongest evidence is the CVE description, affected-version range, upstream commit, and Fedora/Red Hat advisories. The source bundle does not prove real-world exploitation or name all downstream consumers, so validate both dynamic packages and embedded library copies.
Mitigation direction
- Upgrade libyang to 1.0-r5 or later where applicable.
- Apply Red Hat or Fedora fixed packages from the referenced advisories.
- Restrict YANG file ingestion to trusted sources until patched.
- Check vendor guidance for embedded or statically linked libyang copies.
Validation and detection
- Inventory installed and bundled libyang versions across affected systems.
- Confirm package versions are not earlier than 1.0-r5.
- Identify applications that parse YANG files from external users or automation.
- Review Red Hat and Fedora advisory status for managed distributions.
- Check crash telemetry for parser failures involving YANG identityref handling.
Public sources used
Generated from the cited source records. This long-tail analysis has not been individually reviewed by a named human.
Conservative CVE-to-ATT&CK context
These mappings and lookup hints may be relevant to the vulnerability behavior, CWE, affected product, or exposure path. Glexia-inferred context is not an official MITRE, ATT&CK, CWE, or CVE Program mapping.
ATT&CK lookup starting points
Use these exact CWE pages and searches to review the Glexia ATT&CK library from this CVE's weakness and description context.
CWE-121: Exact CWE lookup
Use the exact CWE identifier as the starting point before reviewing related ATT&CK behavior. Open the exact CWE lookup page first, then review the ATT&CK searches from that MITRE weakness context. This is a Glexia lookup hint, not an official ATT&CK mapping.
Open ATT&CK lookupExecution behavior lookup
The CVE wording references code or command execution, so execution technique review may help defensive triage. This is a Glexia inferred lookup path, not an official MITRE, ATT&CK, or CVE Program mapping.
Open ATT&CK lookupCVE-2019-19334 mapping review
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Open ATT&CK lookup- Severity
- High
- CVSS
- 8.1 (3.0)
- Known Exploited
- No
- Published
Vector: CVSS:3.0/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H
CNA and ADP enrichment extracted from CVE v5
These fields come from the CVE record and ADP containers, not from Glexia's Take. They preserve time-varying source decisions such as CISA SSVC, KEV status, CVSS metrics, and provider references.
CVSS vector scores
1 official scoreWe collect every scored CVSS vector available in the official CNA and ADP containers. When more than one version is present, the table keeps the source vectors side by side instead of collapsing them into the highest score.
CVSS:3.0/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H2.25.9Primary CVE scoreVulnerability scoring details
Base CVSS 3.0 score
8.1HighVector: CVSS:3.0/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H
Source materials
- CVE List V5 sourceCVE List V5
- https://bugzilla.redhat.com/show_bug.cgi?id=CVE-2019-19334CVE reference · x_refsource_CONFIRM
- https://github.com/CESNET/libyang/commit/6980afae2ff9fcd6d67508b0a3f694d75fd059d6CVE reference · x_refsource_CONFIRM
- FEDORA-2019-dfe0b42bc5CVE reference · vendor-advisory, x_refsource_FEDORA
- FEDORA-2019-9d83929ffaCVE reference · vendor-advisory, x_refsource_FEDORA
- RHSA-2019:4360CVE reference · vendor-advisory, x_refsource_REDHAT
Products and packages named in the record
CWE details
CWE links open Glexia weakness intelligence pages with official CWE context, developer remediation guidance, and related CVE mappings.
Stack-based Buffer Overflow
Stack-based Buffer Overflow represents a recurring weakness pattern that can create exploitable paths when design, validation, or implementation controls are missing.