# CVE-2021-28550: Adobe Acrobat and Reader Use-After-Free

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

- **Severity:** Critical 9.6 (`CVSS:3.0/AV:N/AC:L/PR:N/UI:R/S:C/C:H/I:H/A:H`)
- **Exploited in the wild:** Yes, since 3 Nov 2021 (CISA KEV)
- **Login needed:** Not needed
- **Attackable:** Over the internet
- **Victim action needed:** A user has to click or open something
- **Fix available:** No
- **Published:** 2 Sep 2021
- **Updated:** 21 Oct 2025
- **Also known as:** GHSA-865h-4rjv-52pg

## What is CVE-2021-28550?

CVE-2021-28550 is a critical use after free vulnerability in Adobe Acrobat, published on 2 Sep 2021. An attacker can exploit it over the internet without logging in, and only if a user opens a file or follows a link.

### Official description

Acrobat Reader DC versions versions 2021.001.20150 (and earlier), 2020.001.30020 (and earlier) and 2017.011.30194 (and earlier) are affected by a 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-2021-28550?

It affects 4 products.


Products: Adobe Acrobat, Adobe Acrobat Dc, Adobe Acrobat Reader, Adobe Acrobat Reader Dc.

## How do I fix CVE-2021-28550?

No fix has been published for CVE-2021-28550 yet. Limit exposure of the affected software until one is available. US federal agencies must fix it by 17 Nov 2021.

## Is CVE-2021-28550 being exploited?

Yes. Attackers have exploited CVE-2021-28550 in the wild since at least 3 Nov 2021.

## Other vulnerabilities in Adobe Acrobat

- [CVE-2021-21017](https://insights.sbomify.com/CVE-2021-21017/): Adobe Acrobat and Reader Heap-based Buffer Overflow (high 8.8, exploited in the wild)
- [CVE-2014-0546](https://insights.sbomify.com/CVE-2014-0546/): Adobe Reader and Acrobat Sandbox Bypass (high 8.8, exploited in the wild)
- [CVE-2014-0496](https://insights.sbomify.com/CVE-2014-0496/): Adobe Reader and Acrobat Use-After-Free (high 8.8, exploited in the wild)
- [CVE-2013-3346](https://insights.sbomify.com/CVE-2013-3346/): Adobe Reader and Acrobat Memory Corruption (high 8.8, exploited in the wild)
- [CVE-2013-2729](https://insights.sbomify.com/CVE-2013-2729/): Adobe Reader and Acrobat Arbitrary Integer Overflow (high 8.8, exploited in the wild)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2021-28550 and fix it if it is affected.

What it is: CVE-2021-28550 is a critical use after free vulnerability in Adobe Acrobat, published on 2 Sep 2021. An attacker can exploit it over the internet without logging in, and only if a user opens a file or follows a link.
Exploitation: Yes. Attackers have exploited CVE-2021-28550 in the wild since at least 3 Nov 2021.

Affected product: Adobe Acrobat. 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-2021-28550/ (Markdown: https://insights.sbomify.com/CVE-2021-28550/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2021-28550
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2021-28550
- OSV: https://osv.dev/vulnerability/CVE-2021-28550

---
From sbomify Insights: https://insights.sbomify.com/CVE-2021-28550/
Summaries are generated and may contain mistakes; the official description above is the record.