# CVE-2021-36978: Memory corruption in n/a

> A heap-based buffer overflow in QPDF allows attackers to execute arbitrary code or cause denial of service via crafted PDF files.

- **Severity:** Medium 5.5 (`CVSS:3.1/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:** 20 Jul 2021
- **Updated:** 15 Oct 2024
- **Also known as:** DEBIAN-CVE-2021-36978, GHSA-vgrr-57vg-f5rq, SUSE-SU-2022:3248-1, UBUNTU-CVE-2021-36978

## What is CVE-2021-36978?

CVE-2021-36978 is a medium-severity memory corruption vulnerability in n/a, published on 20 Jul 2021. 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

QPDF 9.x through 9.1.1 and 10.x through 10.0.4 has a heap-based buffer overflow in Pl_ASCII85Decoder::write (called from Pl_AES_PDF::flush and Pl_AES_PDF::finish) when a certain downstream write fails.

Weakness: CWE-787 (Out-of-bounds Write)

## Which versions are affected by CVE-2021-36978?

It affects 1 product.


| Package | Ecosystem | Affected | Fixed in |
| --- | --- | --- | --- |
| `qpdf` | SUSE:Enterprise Storage 7 | All versions | 9.0.2-150200.3.3.1 |
| `qpdf` | SUSE:Linux Enterprise High Performance Computing 15 SP2-ESPOS | All versions | 9.0.2-150200.3.3.1 |
| `qpdf` | SUSE:Linux Enterprise High Performance Computing 15 SP2-LTSS | All versions | 9.0.2-150200.3.3.1 |
| `qpdf` | SUSE:Linux Enterprise Module for Basesystem 15 SP3 | All versions | 9.0.2-150200.3.3.1 |
| `qpdf` | SUSE:Linux Enterprise Module for Basesystem 15 SP4 | All versions | 9.0.2-150200.3.3.1 |
| `qpdf` | SUSE:Linux Enterprise Server 15 SP2-BCL | All versions | 9.0.2-150200.3.3.1 |
| `qpdf` | SUSE:Linux Enterprise Server 15 SP2-LTSS | All versions | 9.0.2-150200.3.3.1 |
| `qpdf` | SUSE:Linux Enterprise Server for SAP Applications 15 SP2 | All versions | 9.0.2-150200.3.3.1 |
| `qpdf` | SUSE:Manager Proxy 4.1 | All versions | 9.0.2-150200.3.3.1 |
| `qpdf` | SUSE:Manager Retail Branch Server 4.1 | All versions | 9.0.2-150200.3.3.1 |
| `qpdf` | SUSE:Manager Server 4.1 | All versions | 9.0.2-150200.3.3.1 |
| `qpdf` | openSUSE:Leap 15.3 | All versions | 9.0.2-150200.3.3.1 |
| `qpdf` | openSUSE:Leap 15.4 | All versions | 9.0.2-150200.3.3.1 |

Products: Qpdf Project Qpdf.

## How do I fix CVE-2021-36978?

Upgrade to a fixed version.

## Is CVE-2021-36978 being exploited?

There is no known exploitation of CVE-2021-36978 in the wild and no public exploit code.

## Other vulnerabilities in n/a

- [CVE-2017-12595](https://insights.sbomify.com/CVE-2017-12595/): Denial of service in n/a (high 7.8)
- [CVE-2022-34503](https://insights.sbomify.com/CVE-2022-34503/): Memory corruption in n/a (medium 6.5)
- [CVE-2015-9252](https://insights.sbomify.com/CVE-2015-9252/): Denial of service in n/a (medium 5.5)
- [CVE-2017-18183](https://insights.sbomify.com/CVE-2017-18183/): Denial of service in n/a (medium 5.5)
- [CVE-2017-18184](https://insights.sbomify.com/CVE-2017-18184/): Memory corruption in n/a (medium 5.5)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2021-36978 and fix it if it is affected.

What it is: CVE-2021-36978 is a medium-severity memory corruption vulnerability in n/a, published on 20 Jul 2021. 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-2021-36978 in the wild and no public exploit code.

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-2021-36978/ (Markdown: https://insights.sbomify.com/CVE-2021-36978/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2021-36978
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2021-36978
- OSV: https://osv.dev/vulnerability/CVE-2021-36978

---
From sbomify Insights: https://insights.sbomify.com/CVE-2021-36978/
Summaries are generated and may contain mistakes; the official description above is the record.