# CVE-2020-36430: Memory corruption in n/a

> A heap-based buffer overflow in libass allows attackers to execute arbitrary code or cause denial of service via crafted font data.

- **Severity:** High 7.8 (`CVSS:3.1/AV:L/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:** Local or same network only
- **Victim action needed:** A user has to click or open something
- **Fix available:** Yes
- **Published:** 20 Jul 2021
- **Updated:** 4 Aug 2024
- **Also known as:** DEBIAN-CVE-2020-36430, GHSA-pqvw-6c6x-gvwh, MGASA-2021-0413, OESA-2021-1303, SUSE-SU-2021:2792-1, openSUSE-SU-2021:1174-1, openSUSE-SU-2021:2792-1

## What is CVE-2020-36430?

CVE-2020-36430 is a high-severity memory corruption vulnerability in Fedoraproject Fedora, published on 20 Jul 2021. It can only be exploited from the same machine or local network, and only if a user opens a file or follows a link.

### Official description

libass 0.15.x before 0.15.1 has a heap-based buffer overflow in decode_chars (called from decode_font and process_text) because the wrong integer data type is used for subtraction.

Weakness: CWE-787 (Out-of-bounds Write)

## Which versions are affected by CVE-2020-36430?

It affects 2 products.


| Package | Ecosystem | Affected | Fixed in |
| --- | --- | --- | --- |
| `libass` | SUSE:Enterprise Storage 6 | All versions | 0.14.0-3.9.1 |
| `libass` | SUSE:Linux Enterprise High Performance Computing 15 SP1-ESPOS | All versions | 0.14.0-3.9.1 |
| `libass` | SUSE:Linux Enterprise High Performance Computing 15 SP1-LTSS | All versions | 0.14.0-3.9.1 |
| `libass` | SUSE:Linux Enterprise High Performance Computing 15-ESPOS | All versions | 0.14.0-3.9.1 |
| `libass` | SUSE:Linux Enterprise High Performance Computing 15-LTSS | All versions | 0.14.0-3.9.1 |
| `libass` | SUSE:Linux Enterprise Module for Desktop Applications 15 SP2 | All versions | 0.14.0-3.9.1 |
| `libass` | SUSE:Linux Enterprise Module for Desktop Applications 15 SP3 | All versions | 0.14.0-3.9.1 |
| `libass` | SUSE:Linux Enterprise Server 15 SP1-BCL | All versions | 0.14.0-3.9.1 |
| `libass` | SUSE:Linux Enterprise Server 15 SP1-LTSS | All versions | 0.14.0-3.9.1 |
| `libass` | SUSE:Linux Enterprise Server 15-LTSS | All versions | 0.14.0-3.9.1 |
| `libass` | SUSE:Linux Enterprise Server for SAP Applications 15 | All versions | 0.14.0-3.9.1 |
| `libass` | SUSE:Linux Enterprise Server for SAP Applications 15 SP1 | All versions | 0.14.0-3.9.1 |
| `libass` | SUSE:Manager Proxy 4.0 | All versions | 0.14.0-3.9.1 |
| `libass` | SUSE:Manager Retail Branch Server 4.0 | All versions | 0.14.0-3.9.1 |
| `libass` | SUSE:Manager Server 4.0 | All versions | 0.14.0-3.9.1 |
| `libass` | openSUSE:Leap 15.2 | All versions | 0.14.0-lp152.4.9.1 |
| `libass` | openSUSE:Leap 15.3 | All versions | 0.14.0-3.9.1 |

Products: Fedoraproject Fedora, Libass Project Libass.

## How do I fix CVE-2020-36430?

Upgrade to a fixed version.

## Is CVE-2020-36430 being exploited?

There is no known exploitation of CVE-2020-36430 in the wild and no public exploit code.

## Other vulnerabilities in Fedoraproject Fedora

- [CVE-2024-4577](https://insights.sbomify.com/CVE-2024-4577/): PHP-CGI OS Command Injection (critical 9.8, exploited in the wild)
- [CVE-2021-39226](https://insights.sbomify.com/CVE-2021-39226/): Grafana Authentication Bypass (critical 9.8, exploited in the wild)
- [CVE-2019-5544](https://insights.sbomify.com/CVE-2019-5544/): VMware ESXi and Horizon DaaS OpenSLP Heap-Based Buffer Overflow (critical 9.8, exploited in the wild)
- [CVE-2024-4947](https://insights.sbomify.com/CVE-2024-4947/): Google Chromium V8 Type Confusion (critical 9.6, exploited in the wild)
- [CVE-2024-4671](https://insights.sbomify.com/CVE-2024-4671/): Google Chromium Visuals Use-After-Free (critical 9.6, exploited in the wild)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2020-36430 and fix it if it is affected.

What it is: CVE-2020-36430 is a high-severity memory corruption vulnerability in Fedoraproject Fedora, published on 20 Jul 2021. It can only be exploited from the same machine or local network, and only if a user opens a file or follows a link.
Exploitation: There is no known exploitation of CVE-2020-36430 in the wild and no public exploit code.

Affected product: Fedoraproject Fedora. 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-2020-36430/ (Markdown: https://insights.sbomify.com/CVE-2020-36430/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2020-36430
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2020-36430
- OSV: https://osv.dev/vulnerability/CVE-2020-36430

---
From sbomify Insights: https://insights.sbomify.com/CVE-2020-36430/
Summaries are generated and may contain mistakes; the official description above is the record.