6.1

CVE-2025-3859: mozilla firefox_focus Open Redirect

CVSS: 6.1v3.1MediumModified
Published 30-04-2025Last modified 13-04-2026
Open JSON

Vulnerability summary

CVE-2025-3859 is a medium (CVSS 6.1) Open Redirect vulnerability in mozilla firefox_focus. EPSS estimates a 0.20% chance of exploitation in the next 30 days, higher than 9.7% of scored vulnerabilities.

Overall risk
24/100
0100
Low · default modelHow is this calculated?
CVSS score
6.1/10
010
Medium · v3.1 (NVD)
EPSS score
0.20%
0%100%
Low · +0.01 pp in 30 days
KEVNot listedIn no KEV catalog
RansomwareNone recordedNo known use recorded
Public exploits0No public exploits recorded

Timeline

  1. 30-04-2025
    PublishedVulnerability first disclosed.
  2. 13-04-2026
    Last modifiedVulnerability information updated.

Description

Websites directing users to long URLs that caused eliding to occur in the location view could leverage the truncating behavior to potentially trick users into thinking they were on a different webpage. This vulnerability was fixed in Focus 138.

CVSS metrics

2 scores · 2 sources · 1 version

EPSS trend

Probability

0.20%

Chance of exploitation in the next 30 days

Percentile

10%

Versus all other CVEs

30-day change

+0.01 pp

From 0.20% on 18-09-2026

18-09-202618-10-2026
EPSS score
0.20%

Known exploited

Compare KEV catalogs

Not in any of the 3 tracked catalogs.

Public exploits

0 found

No public exploits indexed.

Weaknesses

CWE · root cause

Affected systems

Mozilla1 product

1 vendor · 1 product

References

2 links