What is CVE-2021-34823?

CVE-2021-34823 is a critical-severity vulnerability in On24 Screenshare, classified under Improper Restriction of XML External Entity Reference (XXE). CVSS score: 9.1/10. Published 2021-08-13.

How severe is CVE-2021-34823?

Critical severity. CVSS v3 base score is 9.1 out of 10.

XXE in On24 Screenshare

CVE-2021-34823

The ON24 ScreenShare (aka DesktopScreenShare.app) plugin before 2.0 for macOS allows remote file access via its built-in HTTP server. This allows unauthenticated remote users to retrieve files accessible to the logged-on macOS user. When a remote user sends a crafted HTTP request to the server, it triggers a code path that will download a configuration file from a specified remote machine over HTTP. There is an XXE flaw in processing of this configuration file that allows reading local (to macOS) files and uploading them to remote machines.

Vulnerability class: XXE (XML External Entity)

EPSS: 0.020 (78.5th percentile) — read the EPSS interpretation.

CVSS v3 metric

CVSS v3 base score 9.1 (Critical). Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N.

Affected products

On24 Screenshare
N/a — versions n/a

Weakness classification (CWE)

CWE-611 — Improper Restriction of XML External Entity Reference (XXE)

References

cve@mitre.org (Third Party Advisory, x_refsource_MISC)
cve@mitre.org (Third Party Advisory, x_refsource_MISC)

Frequently asked questions

What is CVE-2021-34823?: CVE-2021-34823 is a critical-severity vulnerability in On24 Screenshare, classified under Improper Restriction of XML External Entity Reference (XXE). CVSS score: 9.1/10. Published 2021-08-13.
How severe is CVE-2021-34823?: Critical severity. CVSS v3 base score is 9.1 out of 10.