# CVE-2019-19956: Denial of service in n/a

> A memory leak in libxml2 allows attackers to cause denial of service by exhausting system memory through crafted XML input.

- **Severity:** High 7.5 (`CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** Yes
- **Published:** 24 Dec 2019
- **Updated:** 14 Oct 2026
- **Also known as:** ALPINE-CVE-2019-19956, DEBIAN-CVE-2019-19956, DLA-2048-1, ECHO-36f8-7dd5-7a33, GHSA-5cvc-j2xm-h554, JLSEC-2025-66, MGASA-2020-0020, MGASA-2020-0271, SUSE-SU-2020:1532-1, SUSE-SU-2020:1532-2, UBUNTU-CVE-2019-19956, openSUSE-SU-2020:0781-1

## What is CVE-2019-19956?

CVE-2019-19956 is a high-severity denial of service vulnerability in Canonical Ubuntu Linux, published on 24 Dec 2019. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official description

xmlParseBalancedChunkMemoryRecover in parser.c in libxml2 before 2.9.10 has a memory leak related to newDoc->oldNs.

Weakness: CWE-401 (Missing Release of Memory after Effective Lifetime), CWE-772 (Missing Release of Resource after Effective Lifetime)

## Which versions are affected by CVE-2019-19956?

It affects 12 products.


| Package | Ecosystem | Affected | Fixed in |
| --- | --- | --- | --- |
| `libxml2` | SUSE:Linux Enterprise Module for Basesystem 15 SP1 | All versions | 2.9.7-3.22.1 |
| `python-libxml2-python` | SUSE:Linux Enterprise Module for Basesystem 15 SP1 | All versions | 2.9.7-3.22.1 |
| `libxml2` | SUSE:Linux Enterprise Module for Basesystem 15 SP2 | All versions | 2.9.7-3.22.1 |
| `python-libxml2-python` | SUSE:Linux Enterprise Module for Basesystem 15 SP2 | All versions | 2.9.7-3.22.1 |
| `python-libxml2-python` | SUSE:Linux Enterprise Module for Python 2 15 SP1 | All versions | 2.9.7-3.22.1 |
| `python-libxml2-python` | SUSE:Linux Enterprise Module for Python 2 15 SP2 | All versions | 2.9.7-3.22.1 |
| `libxml2` | openSUSE:Leap 15.1 | All versions | 2.9.7-lp151.5.12.1 |
| `python-libxml2-python` | openSUSE:Leap 15.1 | All versions | 2.9.7-lp151.5.12.1 |

Products: Canonical Ubuntu Linux, Debian Debian Linux, Fedoraproject Fedora, Netapp Active Iq Unified Manager, Netapp Clustered Data Ontap, Netapp Clustered Data Ontap Antivirus Connector, Netapp Manageability Software Development Kit, Netapp Ontap Select Deploy Administration Utility, Netapp Steelstore Cloud Integrated Storage, Oracle Real User Experience Insight, Siemens Sinema Remote Connect Server, Xmlsoft Libxml2.

## How do I fix CVE-2019-19956?

Upgrade to a fixed version.

## Is CVE-2019-19956 being exploited?

There is no known exploitation of CVE-2019-19956 in the wild and no public exploit code.

## Other vulnerabilities in Canonical Ubuntu Linux

- [CVE-2020-11651](https://insights.sbomify.com/CVE-2020-11651/): SaltStack Salt Authentication Bypass (critical 9.8, exploited in the wild)
- [CVE-2020-7247](https://insights.sbomify.com/CVE-2020-7247/): OpenSMTPD Remote Code Execution (critical 9.8, exploited in the wild)
- [CVE-2019-16928](https://insights.sbomify.com/CVE-2019-16928/): Exim Out-of-bounds Write (critical 9.8, exploited in the wild)
- [CVE-2018-6789](https://insights.sbomify.com/CVE-2018-6789/): Exim Buffer Overflow (critical 9.8, exploited in the wild)
- [CVE-2015-2590](https://insights.sbomify.com/CVE-2015-2590/): Oracle Java SE and Java SE Embedded Remote Code Execution (critical 9.8, exploited in the wild)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2019-19956 and fix it if it is affected.

What it is: CVE-2019-19956 is a high-severity denial of service vulnerability in Canonical Ubuntu Linux, published on 24 Dec 2019. An attacker can exploit it over the internet without logging in, with no action from the victim.
Exploitation: There is no known exploitation of CVE-2019-19956 in the wild and no public exploit code.

Affected product: Canonical Ubuntu Linux. 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-2019-19956/ (Markdown: https://insights.sbomify.com/CVE-2019-19956/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2019-19956
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2019-19956
- OSV: https://osv.dev/vulnerability/CVE-2019-19956

---
From sbomify Insights: https://insights.sbomify.com/CVE-2019-19956/
Summaries are generated and may contain mistakes; the official description above is the record.