# CVE-2018-18459: Null dereference in n/a

> Remote attackers can cause a denial of service via a crafted PDF file due to a NULL pointer dereference in the DCTStream::getBlock function.

- **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:** No
- **Published:** 18 Oct 2018
- **Updated:** 5 Aug 2024
- **Also known as:** DEBIAN-CVE-2018-18459, GHSA-6p6g-2h65-337p, UBUNTU-CVE-2018-18459

## What is CVE-2018-18459?

CVE-2018-18459 is a medium-severity vulnerability in Xpdfreader Xpdf, published on 18 Oct 2018. 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

The function DCTStream::getBlock in Stream.cc in Xpdf 4.00 allows remote attackers to cause a denial of service (NULL pointer dereference) via a crafted pdf file, as demonstrated by pdftoppm.

Weakness: CWE-476 (NULL Pointer Dereference)

## Which versions are affected by CVE-2018-18459?

It affects 1 product.


Products: Xpdfreader Xpdf.

## How do I fix CVE-2018-18459?

No fix has been published for CVE-2018-18459 yet. Limit exposure of the affected software until one is available.

## Is CVE-2018-18459 being exploited?

There is no known exploitation of CVE-2018-18459 in the wild and no public exploit code.

## Other vulnerabilities in Xpdfreader Xpdf

- [CVE-2022-38928](https://insights.sbomify.com/CVE-2022-38928/): Null dereference in n/a (high 7.8)
- [CVE-2022-38222](https://insights.sbomify.com/CVE-2022-38222/): Use after free in n/a (high 7.8)
- [CVE-2022-33108](https://insights.sbomify.com/CVE-2022-33108/): Memory corruption in n/a (high 7.8)
- [CVE-2022-30524](https://insights.sbomify.com/CVE-2022-30524/): Memory corruption in n/a (high 7.8)
- [CVE-2020-24996](https://insights.sbomify.com/CVE-2020-24996/): Memory corruption in n/a (high 7.8)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2018-18459 and fix it if it is affected.

What it is: CVE-2018-18459 is a medium-severity vulnerability in Xpdfreader Xpdf, published on 18 Oct 2018. 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-2018-18459 in the wild and no public exploit code.

Affected product: Xpdfreader Xpdf. 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-2018-18459/ (Markdown: https://insights.sbomify.com/CVE-2018-18459/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2018-18459
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2018-18459
- OSV: https://osv.dev/vulnerability/CVE-2018-18459

---
From sbomify Insights: https://insights.sbomify.com/CVE-2018-18459/
Summaries are generated and may contain mistakes; the official description above is the record.