CVE-2021-28133
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.
Does this matter?
EPSS puts the probability of exploitation in the next 30 days at 19.9%, higher than 97% of all known CVEs. Patch or mitigate before the next change window.
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.
- CVSS 3.1
- 4.3 MEDIUMCVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:L/I:N/A:N
- EPSS
- 19.93% probability · 97th percentile
- Public exploits
- None in Exploit-DB
- CISA KEV
- Not listed
- Weakness
- CWE-200
- Affected
- zoom/zoom
- Source
- cve@mitre.org
EPSS moved from 19.9% on 7 October 2026 to 19.9% on 26 October 2026. The dashed line is the ten per cent mark our analysts treat as “patch before the next change window”.
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
Source: NVD record, EPSS from FIRST.org, KEV from CISA, exploits from Exploit-DB. Refreshed daily. Download this record as JSON.