What is CVE-2021-40721?

CVE-2021-40721 is a medium-severity vulnerability in Adobe Connect, classified under Cross-site Scripting. CVSS score: 6.1/10. Published 2021-10-15.

How severe is CVE-2021-40721?

Medium severity. CVSS v3 base score is 6.1 out of 10.

XSS in Adobe Connect

CVE-2021-40721

Adobe Connect version 11.2.3 (and earlier) is affected by a reflected Cross-Site Scripting (XSS) vulnerability. If an attacker is able to convince a victim to visit a URL referencing a vulnerable page, malicious JavaScript content may be executed within the context of the victim's browser.

Vulnerability class: XSS (Cross-Site Scripting)

Published 2021-10-15 · last modified 2026-06-17.

CVSS v3 metric

CVSS v3 base score 6.1 (Medium). Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N.

EPSS exploit prediction

EPSS: 0.010 (61.8th percentile), scored 2026-10-03.

Low probability of exploitation in the next 30 days, but still tracked. 62nd percentile — 61.8% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.

EPSS over last 30 days · oldest: 0.010 · newest: 0.010 · change: 0.000

Affected products

Adobe Connect — versions unspecified

Weakness classification (CWE)

CWE-79 — Cross-site Scripting

References

helpx.adobe.com/security/products/connect/apsb21-91.html (Patch, Release Notes, Vendor Advisory)

Frequently asked questions

What is CVE-2021-40721?: CVE-2021-40721 is a medium-severity vulnerability in Adobe Connect, classified under Cross-site Scripting. CVSS score: 6.1/10. Published 2021-10-15.
How severe is CVE-2021-40721?: Medium severity. CVSS v3 base score is 6.1 out of 10.