CVE-2021-39842 Adobe Acrobat Reader DC messageHandler.OnMessage Use-After-Free Vulnerability

What is CVE-2021-39842?

CVE-2021-39842 is a high-severity use after free vulnerability in Adobe Acrobat, published on 29 Sep 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 2021.005.20060 (and earlier), 2020.004.30006 (and earlier) and 2017.011.30199 (and earlier) are affected by a use-after-free vulnerability that could result in 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

Which versions are affected by CVE-2021-39842?

It affects 4 products.

Products include Adobe Acrobat, Adobe Acrobat Dc, Adobe Acrobat Reader, Adobe Acrobat Reader Dc.

How do I fix CVE-2021-39842?

No fix has been published for CVE-2021-39842 yet. Limit exposure of the affected software until one is available.

Upgrade to the fixed version. These bugs are found with fuzzing and sanitisers and avoided by memory-safe languages. More about Use after free.

Is CVE-2021-39842 being exploited?

There is no known exploitation of CVE-2021-39842 in the wild and no public exploit code.

Other vulnerabilities in Adobe Acrobat

• CVE-2021-28550 Adobe Acrobat and Reader Use-After-Free Exploited Critical 9.6
• CVE-2021-21017 Adobe Acrobat and Reader Heap-based Buffer Overflow Exploited High 8.8
• CVE-2014-0546 Adobe Reader and Acrobat Sandbox Bypass Exploited High 8.8
• CVE-2014-0496 Adobe Reader and Acrobat Use-After-Free Exploited High 8.8
• CVE-2013-3346 Adobe Reader and Acrobat Memory Corruption Exploited High 8.8

All Adobe Acrobat vulnerabilities

Sources

• CVE record
• NVD
• OSV
• GitHub advisory
• How this page is made

Also known as GHSA-m629-r54x-ffhf.