# CVE-2020-27819: Null dereference in libxls

> A remote attacker can cause a denial of service by providing a crafted XLS file to applications using the libxls library.

- **Severity:** Medium 5.5 (`CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:N/I:N/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:** 23 Feb 2021
- **Updated:** 4 Aug 2024
- **Also known as:** GHSA-fp3r-w9w2-jg2f, JLSEC-2026-1294, UBUNTU-CVE-2020-27819, openSUSE-SU-2021:0812-1, openSUSE-SU-2024:11015-1

## What is CVE-2020-27819?

CVE-2020-27819 is a medium-severity vulnerability in libxls, published on 23 Feb 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

An issue was discovered in libxls before and including 1.6.1 when reading Microsoft Excel files. A NULL pointer dereference vulnerability exists when parsing XLS cells in libxls/xls2csv.c:199. It could allow a remote attacker to cause a denial of service via crafted XLS file.

Weakness: CWE-476 (NULL Pointer Dereference)

## Which versions are affected by CVE-2020-27819?

It affects 1 product.


| Package | Ecosystem | Affected | Fixed in |
| --- | --- | --- | --- |
| `libxls` | openSUSE:Leap 15.2 | All versions | 1.6.2-lp152.2.3.1 |

Products: Libxls Project Libxls.

## How do I fix CVE-2020-27819?

Upgrade to a fixed version.

## Is CVE-2020-27819 being exploited?

There is no known exploitation of CVE-2020-27819 in the wild and no public exploit code.

## Other vulnerabilities in libxls

- [CVE-2017-2910](https://insights.sbomify.com/CVE-2017-2910/): Memory corruption in libxls (high 8.8)
- [CVE-2018-20452](https://insights.sbomify.com/CVE-2018-20452/): Use after free in n/a (high 8.8)
- [CVE-2017-12108](https://insights.sbomify.com/CVE-2017-12108/): Integer overflow in libxls (high 8.8)
- [CVE-2017-12109](https://insights.sbomify.com/CVE-2017-12109/): Integer overflow in libxls (high 8.8)
- [CVE-2017-12110](https://insights.sbomify.com/CVE-2017-12110/): Integer overflow in libxls (high 8.8)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2020-27819 and fix it if it is affected.

What it is: CVE-2020-27819 is a medium-severity vulnerability in libxls, published on 23 Feb 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-2020-27819 in the wild and no public exploit code.

Affected product: libxls. 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-2020-27819/ (Markdown: https://insights.sbomify.com/CVE-2020-27819/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2020-27819
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2020-27819
- OSV: https://osv.dev/vulnerability/CVE-2020-27819

---
From sbomify Insights: https://insights.sbomify.com/CVE-2020-27819/
Summaries are generated and may contain mistakes; the official description above is the record.