# CVE-2021-28639: Adobe Acrobat Reader DC setAction Use-After-Free Remote Code Execution Vulnerability

> An attacker can achieve arbitrary code execution by tricking a user into opening a malicious file in Adobe Acrobat Reader.

- **Severity:** High 7.8 (`CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:H/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:** 20 Aug 2021
- **Updated:** 16 Sep 2024
- **Also known as:** GHSA-wv7j-84hj-89vg

## What is CVE-2021-28639?

CVE-2021-28639 is a high-severity use after free vulnerability in Adobe Acrobat Dc, published on 20 Aug 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

Acrobat Reader DC versions 2021.005.20054 (and earlier), 2020.004.30005 (and earlier) and 2017.011.30197 (and earlier) are affected by an Use-after-free vulnerability. An unauthenticated attacker could leverage this vulnerability to achieve arbitrary code execution in the context of the current user. Exploitation of this issue requires user interaction in that a victim must open a malicious file.

Weakness: CWE-416 (Use After Free)

## Which versions are affected by CVE-2021-28639?

It affects 2 products.


Products: Adobe Acrobat Dc, Adobe Acrobat Reader Dc.

## How do I fix CVE-2021-28639?

No fix has been published for CVE-2021-28639 yet. Limit exposure of the affected software until one is available.

## Is CVE-2021-28639 being exploited?

There is no known exploitation of CVE-2021-28639 in the wild and no public exploit code.

## Other vulnerabilities in Adobe Acrobat Dc

- [CVE-2018-4990](https://insights.sbomify.com/CVE-2018-4990/): Adobe Acrobat and Reader Double Free (high 8.8, exploited in the wild)
- [CVE-2020-9715](https://insights.sbomify.com/CVE-2020-9715/): Adobe Acrobat Use-After-Free (high 7.8, exploited in the wild)
- [CVE-2020-3792](https://insights.sbomify.com/CVE-2020-3792/): Use after free in Adobe Acrobat and Reader (critical 9.8)
- [CVE-2020-3793](https://insights.sbomify.com/CVE-2020-3793/): Use after free in Adobe Acrobat and Reader (critical 9.8)
- [CVE-2020-3795](https://insights.sbomify.com/CVE-2020-3795/): Memory corruption in Adobe Acrobat and Reader (critical 9.8)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2021-28639 and fix it if it is affected.

What it is: CVE-2021-28639 is a high-severity use after free vulnerability in Adobe Acrobat Dc, published on 20 Aug 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-2021-28639 in the wild and no public exploit code.

Affected product: Adobe Acrobat Dc. 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-2021-28639/ (Markdown: https://insights.sbomify.com/CVE-2021-28639/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2021-28639
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2021-28639
- OSV: https://osv.dev/vulnerability/CVE-2021-28639

---
From sbomify Insights: https://insights.sbomify.com/CVE-2021-28639/
Summaries are generated and may contain mistakes; the official description above is the record.