# CVE-2019-20393: Memory corruption in n/a

> A double-free vulnerability in libyang allows attackers to cause crashes or execute code via malicious YANG files.

- **Severity:** High 8.8 (`CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Over the internet
- **Victim action needed:** A user has to click or open something
- **Fix available:** Yes
- **Published:** 22 Jan 2020
- **Updated:** 5 Aug 2024
- **Also known as:** DEBIAN-CVE-2019-20393, GHSA-xr5g-jrq4-w3j4, UBUNTU-CVE-2019-20393

## What is CVE-2019-20393?

CVE-2019-20393 is a high-severity memory corruption vulnerability in n/a, published on 22 Jan 2020. An attacker can exploit it over the internet without logging in, and only if a user opens a file or follows a link.

### Official description

A double-free is present in libyang before v1.0-r1 in the function yyparse() when an empty description is used. 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.

Weakness: CWE-415 (Double Free)

## Which versions are affected by CVE-2019-20393?

It affects 1 product.


Products: Cesnet Libyang.

## How do I fix CVE-2019-20393?

Upgrade to a fixed version.

## Is CVE-2019-20393 being exploited?

There is no known exploitation of CVE-2019-20393 in the wild and no public exploit code.

## Other vulnerabilities in n/a

- [CVE-2019-20394](https://insights.sbomify.com/CVE-2019-20394/): Use after free in n/a (high 8.8)
- [CVE-2019-20397](https://insights.sbomify.com/CVE-2019-20397/): Memory corruption in n/a (high 8.8)
- [CVE-2019-19333](https://insights.sbomify.com/CVE-2019-19333/): Memory corruption in libyang (high 8.1)
- [CVE-2019-19334](https://insights.sbomify.com/CVE-2019-19334/): Memory corruption in libyang (high 8.1)
- [CVE-2023-26917](https://insights.sbomify.com/CVE-2023-26917/): Null dereference in n/a (high 7.5)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2019-20393 and fix it if it is affected.

What it is: CVE-2019-20393 is a high-severity memory corruption vulnerability in n/a, published on 22 Jan 2020. An attacker can exploit it over the internet without logging in, and only if a user opens a file or follows a link.
Exploitation: There is no known exploitation of CVE-2019-20393 in the wild and no public exploit code.

Affected product: n/a. No package-level version data is available, so check the vendor advisory linked from the reference page.

Task:
1. Search the dependency manifests and lockfiles (for example package.json, package-lock.json, requirements.txt, poetry.lock, uv.lock, pom.xml, build.gradle, go.mod, Cargo.lock, Gemfile.lock) and any Dockerfiles for the affected packages, including transitive dependencies.
2. If an affected version is in use, upgrade it to the fixed version for its release line with the project's package manager, so the lockfile is regenerated. Prefer the smallest upgrade that fixes it.
3. If there is no fix, or the upgrade would break the build, do not guess: explain the risk and the safest workaround instead.
4. Run the tests and summarise what changed and why.
5. If nothing in the project is affected, say so and change nothing.

Reference: https://insights.sbomify.com/CVE-2019-20393/ (Markdown: https://insights.sbomify.com/CVE-2019-20393/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2019-20393
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2019-20393
- OSV: https://osv.dev/vulnerability/CVE-2019-20393

---
From sbomify Insights: https://insights.sbomify.com/CVE-2019-20393/
Summaries are generated and may contain mistakes; the official description above is the record.