What is CVE-2020-7747?

CVE-2020-7747 is a medium-severity vulnerability in Lightning-Viz Lightning, classified under Cross-site Scripting. CVSS score: 6.3/10. Published 2020-10-20.

How severe is CVE-2020-7747?

Medium severity. CVSS v3 base score is 6.3 out of 10.

XSS in Lightning-Viz Lightning

CVE-2020-7747

This affects all versions of package lightning-server. It is possible to inject malicious JavaScript code as part of a session controller.

Vulnerability class: XSS (Cross-Site Scripting)

Published 2020-10-20 · last modified 2026-06-17.

CVSS v3 metric

CVSS v3 base score 6.3 (Medium). Vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:U/C:H/I:L/A:N.

EPSS exploit prediction

EPSS: 0.009 (57.1th percentile), scored 2026-10-05.

Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 57th percentile — 57.1% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.

EPSS over last 30 days · oldest: 0.009 · newest: 0.009 · change: 0.000

Affected products

Lightning-Viz Lightning
Lightning-Server — versions 0

Weakness classification (CWE)

CWE-79 — Cross-site Scripting

References

snyk.io/vuln/SNYK-JS-LIGHTNINGSERVER-1019381 (Exploit, Third Party Advisory)
github.com/lightning-viz/lightning/blob/master/app/controllers/session.js#L230 (Broken Link)
github.com/lightning-viz/lightning/blob/master/app/controllers/session.js (Exploit, Vendor Advisory)

Frequently asked questions

What is CVE-2020-7747?: CVE-2020-7747 is a medium-severity vulnerability in Lightning-Viz Lightning, classified under Cross-site Scripting. CVSS score: 6.3/10. Published 2020-10-20.
How severe is CVE-2020-7747?: Medium severity. CVSS v3 base score is 6.3 out of 10.