What is CVE-2019-17000?

CVE-2019-17000 is a medium-severity vulnerability in Mozilla Firefox, classified under Cross-site Scripting. CVSS score: 6.1/10. Published 2020-01-08.

How severe is CVE-2019-17000?

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

XSS in Mozilla Firefox

CVE-2019-17000

An object tag with a data URI did not correctly inherit the document's Content Security Policy. This allowed a CSP bypass in a cross-origin frame if the document's policy explicitly allowed data: URIs. This vulnerability affects Firefox < 70.

Vulnerability class: XSS (Cross-Site Scripting)

Published 2020-01-08 · 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: 0.008 (56.4th percentile), scored 2026-10-25.

Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 56th percentile — 56.4% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.

EPSS over last 30 days · oldest: 0.008 · newest: 0.008 · change: 0.000

Affected products

Mozilla Firefox — versions before 70

Weakness classification (CWE)

CWE-79 — Cross-site Scripting

References

bugzilla.mozilla.org/show_bug.cgi (Permissions Required)
www.mozilla.org/security/advisories/mfsa2019-34/ (Vendor Advisory)

Frequently asked questions

What is CVE-2019-17000?: CVE-2019-17000 is a medium-severity vulnerability in Mozilla Firefox, classified under Cross-site Scripting. CVSS score: 6.1/10. Published 2020-01-08.
How severe is CVE-2019-17000?: Medium severity. CVSS v3 base score is 6.1 out of 10.