What is CVE-2021-39843?

CVE-2021-39843 is a high-severity vulnerability in Adobe Acrobat, classified under Out-of-bounds Write. CVSS score: 7.8/10. Published 2021-09-29.

How severe is CVE-2021-39843?

High severity. CVSS v3 base score is 7.8 out of 10.

Buffer overflow in Adobe Acrobat

CVE-2021-39843

Acrobat Reader DC versions 2021.005.20060 (and earlier), 2020.004.30006 (and earlier) and 2017.011.30199 (and earlier) are affected by an out-of-bounds write 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.

Vulnerability class: Buffer Overflow

Published 2021-09-29 · last modified 2026-06-17.

CVSS v3 metric

CVSS v3 base score 7.8 (High). Vector: CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H.

EPSS exploit prediction

EPSS: 0.767 (99.5th percentile), scored 2026-10-29.

High probability of exploitation in the next 30 days — patch promptly. 100th percentile — 99.5% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.

EPSS over last 30 days · oldest: 0.767 · newest: 0.767 · change: 0.000

Affected products

Adobe Acrobat
Adobe Acrobat Dc
Adobe Acrobat Reader — versions unspecified
Adobe Acrobat Reader
Adobe Acrobat Reader Dc
Apple macOS
Microsoft Windows

Weakness classification (CWE)

CWE-787 — Out-of-bounds Write

References

helpx.adobe.com/security/products/acrobat/apsb21-55.html (Release Notes, Vendor Advisory)

Frequently asked questions

What is CVE-2021-39843?: CVE-2021-39843 is a high-severity vulnerability in Adobe Acrobat, classified under Out-of-bounds Write. CVSS score: 7.8/10. Published 2021-09-29.
How severe is CVE-2021-39843?: High severity. CVSS v3 base score is 7.8 out of 10.