Vulnerability in Mozilla Firefox

CVE-2025-5020

Opening maliciously-crafted URLs in Firefox from other apps such as Safari could have allowed attackers to spoof website addresses if the URLs utilized non-HTTP schemes used internally by the Firefox iOS client. This vulnerability was fixed in Firefox for iOS 139.

Published · last modified .

CVSS v3 metric

CVSS v3 base score 4.3 (Medium). Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:L/A:N.

EPSS exploit prediction

EPSS: 0.002 (13.6th percentile), scored .

Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 14th percentile — 13.6% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.

EPSS trend (30 days)EPSS over the last 30 days for CVE-2025-5020: held from 0.002 to 0.002.

EPSS over last 30 days · oldest: 0.002 · newest: 0.002 · change: +0.000

Affected products

Weakness classification (CWE)

Public proof-of-concept exploits

References

Frequently asked questions

What is CVE-2025-5020?
CVE-2025-5020 is a medium-severity vulnerability in Mozilla Firefox, classified under CWE-939. CVSS score: 4.3/10. Published 2025-05-21.
How severe is CVE-2025-5020?
Medium severity. CVSS v3 base score is 4.3 out of 10.
Is CVE-2025-5020 known to be exploited?
1 public proof-of-concept repositories are indexed. Not currently listed in the CISA KEV catalog.