# CVE-2020-24978: Use after free in n/a

> A double-free vulnerability in the NASM assembler's preprocessor allows attackers to execute arbitrary code or cause a denial of service.

- **Severity:** Critical 9.8 (`CVSS:3.1/AV:N/AC:L/PR:N/UI:N/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:** Not needed
- **Fix available:** Yes
- **Published:** 3 Sep 2020
- **Updated:** 4 Aug 2024
- **Also known as:** DEBIAN-CVE-2020-24978, GHSA-4vwx-p2g9-hr37, UBUNTU-CVE-2020-24978

## What is CVE-2020-24978?

CVE-2020-24978 is a critical use after free vulnerability in Nasm Netwide Assembler, published on 3 Sep 2020. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official description

In NASM 2.15.04rc3, there is a double-free vulnerability in pp_tokline asm/preproc.c. This is fixed in commit 8806c3ca007b84accac21dd88b900fb03614ceb7.

Weakness: CWE-415 (Double Free)

## Which versions are affected by CVE-2020-24978?

It affects 1 product.


Products: Nasm Netwide Assembler.

## How do I fix CVE-2020-24978?

Apply the vendor's patch.

## Is CVE-2020-24978 being exploited?

There is no known exploitation of CVE-2020-24978 in the wild and no public exploit code.

## Other vulnerabilities in Nasm Netwide Assembler

- [CVE-2004-1287](https://insights.sbomify.com/CVE-2004-1287/): Memory corruption in n/a (critical 10.0)
- [CVE-2008-7177](https://insights.sbomify.com/CVE-2008-7177/): Memory corruption in n/a (critical 9.3)
- [CVE-2023-31722](https://insights.sbomify.com/CVE-2023-31722/): Memory corruption in n/a (high 7.8)
- [CVE-2022-44370](https://insights.sbomify.com/CVE-2022-44370/): Memory corruption in n/a (high 7.8)
- [CVE-2022-46456](https://insights.sbomify.com/CVE-2022-46456/): Memory corruption in n/a (high 7.8)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2020-24978 and fix it if it is affected.

What it is: CVE-2020-24978 is a critical use after free vulnerability in Nasm Netwide Assembler, published on 3 Sep 2020. 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-2020-24978 in the wild and no public exploit code.

Affected product: Nasm Netwide Assembler. 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-2020-24978/ (Markdown: https://insights.sbomify.com/CVE-2020-24978/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2020-24978
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2020-24978
- OSV: https://osv.dev/vulnerability/CVE-2020-24978

---
From sbomify Insights: https://insights.sbomify.com/CVE-2020-24978/
Summaries are generated and may contain mistakes; the official description above is the record.