# CVE-2018-20651: Null dereference in n/a

> A crafted ELF file causes a NULL pointer dereference in the BFD library, allowing remote attackers to cause a denial of service.

- **Severity:** Medium 5.5 (`CVSS:3.0/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:** 1 Jan 2019
- **Updated:** 5 Aug 2024
- **Also known as:** DEBIAN-CVE-2018-20651, GHSA-w8vj-984w-6pcp, UBUNTU-CVE-2018-20651

## What is CVE-2018-20651?

CVE-2018-20651 is a medium-severity vulnerability in Gnu Binutils, published on 1 Jan 2019. 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

A NULL pointer dereference was discovered in elf_link_add_object_symbols in elflink.c in the Binary File Descriptor (BFD) library (aka libbfd), as distributed in GNU Binutils 2.31.1. This occurs for a crafted ET_DYN with no program headers. A specially crafted ELF file allows remote attackers to cause a denial of service, as demonstrated by ld.

Weakness: CWE-476 (NULL Pointer Dereference)

## Which versions are affected by CVE-2018-20651?

It affects 1 product.


Products: Gnu Binutils.

## How do I fix CVE-2018-20651?

Upgrade to a fixed version.

## Is CVE-2018-20651 being exploited?

There is no known exploitation of CVE-2018-20651 in the wild and no public exploit code.

## Other vulnerabilities in Gnu Binutils

- [CVE-2017-7614](https://insights.sbomify.com/CVE-2017-7614/): Null dereference in n/a (critical 9.8)
- [CVE-2014-9939](https://insights.sbomify.com/CVE-2014-9939/): Memory corruption in n/a (critical 9.8)
- [CVE-2017-7226](https://insights.sbomify.com/CVE-2017-7226/): Information disclosure in n/a (critical 9.1)
- [CVE-2017-6969](https://insights.sbomify.com/CVE-2017-6969/): Information disclosure in n/a (critical 9.1)
- [CVE-2020-19726](https://insights.sbomify.com/CVE-2020-19726/): Denial of service in n/a (high 8.8)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2018-20651 and fix it if it is affected.

What it is: CVE-2018-20651 is a medium-severity vulnerability in Gnu Binutils, published on 1 Jan 2019. 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-2018-20651 in the wild and no public exploit code.

Affected product: Gnu Binutils. 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-2018-20651/ (Markdown: https://insights.sbomify.com/CVE-2018-20651/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2018-20651
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2018-20651
- OSV: https://osv.dev/vulnerability/CVE-2018-20651

---
From sbomify Insights: https://insights.sbomify.com/CVE-2018-20651/
Summaries are generated and may contain mistakes; the official description above is the record.