# CVE-2020-18378: Null dereference in n/a

> A crafted WebAssembly input triggers a null pointer dereference in Binaryen, causing a segmentation fault and denial of service.

- **Severity:** Medium 6.5 (`CVSS:3.1/AV:N/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:** Over the internet
- **Victim action needed:** A user has to click or open something
- **Fix available:** Yes
- **Published:** 22 Aug 2023
- **Updated:** 3 Oct 2024
- **Also known as:** DEBIAN-CVE-2020-18378, GHSA-vj54-ff4j-gq2v, UBUNTU-CVE-2020-18378

## What is CVE-2020-18378?

CVE-2020-18378 is a medium-severity vulnerability in n/a, published on 22 Aug 2023. 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 NULL pointer dereference was discovered in SExpressionWasmBuilder::makeBlock in wasm/wasm-s-parser.c in Binaryen 1.38.26. A crafted wasm input can cause a segmentation fault, leading to denial-of-service, as demonstrated by wasm-as.

Weakness: CWE-476 (NULL Pointer Dereference)

## Which versions are affected by CVE-2020-18378?

It affects 1 product.


Products: Webassembly Binaryen.

## How do I fix CVE-2020-18378?

Upgrade to a fixed version.

## Is CVE-2020-18378 being exploited?

It is not confirmed as exploited in the wild, but public exploit code for CVE-2020-18378 exists.

## Other vulnerabilities in n/a

- [CVE-2020-18382](https://insights.sbomify.com/CVE-2020-18382/): Memory corruption in n/a (medium 6.5)
- [CVE-2019-15758](https://insights.sbomify.com/CVE-2019-15758/): Denial of service in n/a (medium 6.5)
- [CVE-2019-15759](https://insights.sbomify.com/CVE-2019-15759/): Null dereference in n/a (medium 6.5)
- [CVE-2019-7700](https://insights.sbomify.com/CVE-2019-7700/): Memory corruption in n/a (medium 6.5)
- [CVE-2019-7701](https://insights.sbomify.com/CVE-2019-7701/): Memory corruption in n/a (medium 6.5)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2020-18378 and fix it if it is affected.

What it is: CVE-2020-18378 is a medium-severity vulnerability in n/a, published on 22 Aug 2023. An attacker can exploit it over the internet without logging in, and only if a user opens a file or follows a link.
Exploitation: It is not confirmed as exploited in the wild, but public exploit code for CVE-2020-18378 exists.

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-2020-18378/ (Markdown: https://insights.sbomify.com/CVE-2020-18378/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2020-18378
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2020-18378
- OSV: https://osv.dev/vulnerability/CVE-2020-18378

---
From sbomify Insights: https://insights.sbomify.com/CVE-2020-18378/
Summaries are generated and may contain mistakes; the official description above is the record.