CVE-2021-39855

Name: CVE-2021-39855
Creator: NVD / NIST
Published: 2021-09-29T16:15:10.423+00:00
License: https://creativecommons.org/publicdomain/zero/1.0/

MEDIUMCVSS 6.5/10EPSS 2.29%

Last modified Jun 17, 2026

CVE-2021-39855 is a medium-severity vulnerability rated 6.5/10 on the CVSS scale. Acrobat Reader DC ActiveX Control versions 2021.005.20060 (and earlier), 2020.004.30006 (and earlier) and 2017.011.30199 (and earlier) are affected by an Information Disclosure vulnerability. An unauthenticated attacker could leverage this vulnerability to obtain NTLMv2 credentials. EPSS estimates a 2.29% chance of exploitation in the next 30 days.

Description

Acrobat Reader DC ActiveX Control versions 2021.005.20060 (and earlier), 2020.004.30006 (and earlier) and 2017.011.30199 (and earlier) are affected by an Information Disclosure vulnerability. An unauthenticated attacker could leverage this vulnerability to obtain NTLMv2 credentials. Exploitation of this issue requires user interaction in that a victim must open a maliciously crafted Microsoft Office file, or visit an attacker controlled web page.

Metrics

CVSS 3.1

6.5/10

CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:N/A:N

EPSS Probability

2.29%

81.0th percentile

Probability of exploitation in the next 30 days. Learn more

Weakness Enumeration

CWE-200

Affected Software

Vendor	Product	Versions
Adobe	Acrobat	>= 17.011.30059, <= 17.011.30199
Adobe	Acrobat Reader	>= 17.011.30059, <= 17.011.30199
Adobe	Acrobat	>= 20.001.30005, <= 20.004.30006
Adobe	Acrobat Reader	>= 20.001.30005, <= 20.004.30006
Adobe	Acrobat Dc	>= 15.008.20082, <= 21.005.20058
Adobe	Acrobat Reader Dc	>= 15.008.20082, <= 21.005.20058
Adobe	Acrobat Dc	>= 15.008.20082, <= 21.005.20060
Adobe	Acrobat Reader Dc	>= 15.008.20082, <= 21.005.20060

References

https://helpx.adobe.com/security/products/acrobat/apsb21-55.htmlRelease Notes, Vendor Advisory
https://helpx.adobe.com/security/products/acrobat/apsb21-55.htmlRelease Notes, Vendor Advisory

Timeline

Published: Sep 29, 2021
Last Modified: Jun 17, 2026
Status: Modified

Frequently Asked Questions

What is CVE-2021-39855?

How severe is CVE-2021-39855?

CVE-2021-39855 has a CVSS score of 6.5/10 (MEDIUM severity). The EPSS model estimates a 2.29% probability of exploitation in the next 30 days.

How do I fix CVE-2021-39855?

Check the vendor references and advisories linked above for patched versions and mitigation guidance. You can also run a Strix scan to test if your systems are affected.

Are you affected by CVE-2021-39855?

Run a free Strix scan to check your systems for this vulnerability.

Scan your code now

Source: NVD / NIST