CVE-2021-28133

Name: CVE-2021-28133
Creator: NVD / NIST
Published: 2021-03-18T14:15:14.007+00:00
License: https://creativecommons.org/publicdomain/zero/1.0/

MEDIUMCVSS 4.3/10EPSS 16.29%

Last modified Jun 17, 2026

CVE-2021-28133 is a medium-severity vulnerability rated 4.3/10 on the CVSS scale. Zoom through 5.5.4 sometimes allows attackers to read private information on a participant's screen, even though the participant never attempted to share the private part of their screen. When a user shares a specific application window via the Share Screen functionality, other meeting participants can briefly see contents of other application windows that were explicitly not shared. EPSS estimates a 16.29% chance of exploitation in the next 30 days.

Description

Zoom through 5.5.4 sometimes allows attackers to read private information on a participant's screen, even though the participant never attempted to share the private part of their screen. When a user shares a specific application window via the Share Screen functionality, other meeting participants can briefly see contents of other application windows that were explicitly not shared. The contents of these other windows can (for instance) be seen for a short period of time when they overlay the shared window and get into focus. (An attacker can, of course, use a separate screen-recorder application, unsupported by Zoom, to save all such contents for later replays and analysis.) Depending on the unintentionally shared data, this short exposure of screen contents may be a more or less severe security issue.

Metrics

CVSS 3.1

4.3/10

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

EPSS Probability

16.29%

96.5th percentile

Probability of exploitation in the next 30 days. Learn more

Weakness Enumeration

CWE-200

Affected Software

Vendor	Product	Versions
Zoom	Zoom	<= 5.5.4

References

http://packetstormsecurity.com/files/161897/Zoom-5.4.3-54779.1115-5.5.4-13142.0301-Information-Disclosure.htmlThird Party Advisory
http://seclists.org/fulldisclosure/2021/Mar/48Third Party Advisory
https://thehackernews.com/2021/03/new-zoom-screen-sharing-bug-lets-other.htmlThird Party Advisory
https://www.syss.de/fileadmin/dokumente/Publikationen/Advisories/SYSS-2020-044.txtThird Party Advisory
https://www.syss.de/pentest-blog/syss-2020-044-sicherheitsproblem-in-screen-sharing-funktionalitaet-von-zoom-cve-2021-28133Third Party Advisory
https://www.youtube.com/watch?v=SonmmgQlLzgThird Party Advisory
https://zoom.us/trust/security/security-bulletinVendor Advisory
http://packetstormsecurity.com/files/161897/Zoom-5.4.3-54779.1115-5.5.4-13142.0301-Information-Disclosure.htmlThird Party Advisory
http://seclists.org/fulldisclosure/2021/Mar/48Third Party Advisory
https://thehackernews.com/2021/03/new-zoom-screen-sharing-bug-lets-other.htmlThird Party Advisory
https://www.syss.de/fileadmin/dokumente/Publikationen/Advisories/SYSS-2020-044.txtThird Party Advisory
https://www.syss.de/pentest-blog/syss-2020-044-sicherheitsproblem-in-screen-sharing-funktionalitaet-von-zoom-cve-2021-28133Third Party Advisory
https://www.youtube.com/watch?v=SonmmgQlLzgThird Party Advisory
https://zoom.us/trust/security/security-bulletinVendor Advisory

Timeline

Published: Mar 18, 2021
Last Modified: Jun 17, 2026
Status: Modified

Frequently Asked Questions

What is CVE-2021-28133?

How severe is CVE-2021-28133?

CVE-2021-28133 has a CVSS score of 4.3/10 (MEDIUM severity). The EPSS model estimates a 16.29% probability of exploitation in the next 30 days.

How do I fix CVE-2021-28133?

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-2021-28133?

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

Scan your code now

Source: NVD / NIST