# CVE-2021-38563: Null dereference in n/a

> A flaw in Foxit PDF Reader allows attackers to cause a denial of service via a malformed PDF file triggering a null pointer dereference.

- **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:** No
- **Published:** 11 Aug 2021
- **Updated:** 4 Aug 2024
- **Also known as:** GHSA-w5rc-cq4p-9j77

## What is CVE-2021-38563?

CVE-2021-38563 is a critical vulnerability in Foxit Pdf Reader, published on 11 Aug 2021. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official description

An issue was discovered in Foxit PDF Reader before 11.0.1 and PDF Editor before 11.0.1. It mishandles situations in which an array size (derived from a /Size entry) is smaller than the maximum indirect object number, and thus there is an attempted incorrect array access (leading to a NULL pointer dereference, or out-of-bounds read or write).

Weakness: CWE-129 (Improper Validation of Array Index)

## Which versions are affected by CVE-2021-38563?

It affects 2 products.


Products: Foxit Pdf Reader, Foxitsoftware Pdf Editor.

## How do I fix CVE-2021-38563?

No fix has been published for CVE-2021-38563 yet. Limit exposure of the affected software until one is available.

## Is CVE-2021-38563 being exploited?

There is no known exploitation of CVE-2021-38563 in the wild and no public exploit code.

## Other vulnerabilities in Foxit Pdf Reader

- [CVE-2025-32451](https://insights.sbomify.com/CVE-2025-32451/): Memory corruption in Foxit Reader (high 8.8)
- [CVE-2024-28888](https://insights.sbomify.com/CVE-2024-28888/): Use after free in Foxit Reader (high 8.8)
- [CVE-2023-27379](https://insights.sbomify.com/CVE-2023-27379/): Use after free in Foxit Reader (high 8.8)
- [CVE-2023-28744](https://insights.sbomify.com/CVE-2023-28744/): Use after free in Foxit Reader (high 8.8)
- [CVE-2023-32664](https://insights.sbomify.com/CVE-2023-32664/): Memory corruption in Foxit Reader (high 8.8)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2021-38563 and fix it if it is affected.

What it is: CVE-2021-38563 is a critical vulnerability in Foxit Pdf Reader, published on 11 Aug 2021. 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-2021-38563 in the wild and no public exploit code.

Affected product: Foxit Pdf Reader. 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-2021-38563/ (Markdown: https://insights.sbomify.com/CVE-2021-38563/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2021-38563
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2021-38563
- OSV: https://osv.dev/vulnerability/CVE-2021-38563

---
From sbomify Insights: https://insights.sbomify.com/CVE-2021-38563/
Summaries are generated and may contain mistakes; the official description above is the record.