How severe is CVE-2025-3859?

CVE-2025-3859 has a CVSS 3.x base score of 6.1, rated medium severity. It is exploitable over network with low attack complexity, requires no privileges and user interaction. Impact on confidentiality is low, integrity low, and availability none.

Is CVE-2025-3859 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 0% (7th percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2025-3859?

CVE-2025-3859 affects Mozilla Firefox Focus. See the affected-products list for the exact vulnerable versions.

How do I fix CVE-2025-3859?

Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround.

Does CVE-2025-3859 have an EU (EUVD) identifier?

Yes. CVE-2025-3859 is tracked in the ENISA EU Vulnerability Database (EUVD) as EUVD-2025-12733.

When was CVE-2025-3859 published?

CVE-2025-3859 was published on 2025-04-30 and last updated on 2026-06-17.

CVE-2025-3859

CVE-2025-3859 is a medium-severity vulnerability in Mozilla Firefox Focus with a CVSS 3.x base score of 6.1. It is not currently listed as actively exploited by CISA, and its EPSS exploit-prediction score is low. The underlying weakness is classified as CWE-601.

Key facts

Severity: Medium (CVSS 3.x base score 6.1)
EPSS exploit prediction: 0% (7th percentile)
Actively exploited: Not listed in CISA KEV
EU (EUVD) id: EUVD-2025-12733
Weakness: CWE-601
Affected product: Mozilla Firefox Focus
Published: 2025-04-30
Last modified: 2026-06-17

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.

Frequently asked questions

What is CVE-2025-3859?: 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.
How severe is CVE-2025-3859?: CVE-2025-3859 has a CVSS 3.x base score of 6.1, rated medium severity. It is exploitable over network with low attack complexity, requires no privileges and user interaction. Impact on confidentiality is low, integrity low, and availability none.
Is CVE-2025-3859 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 0% (7th percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2025-3859?: CVE-2025-3859 affects Mozilla Firefox Focus. See the affected-products list for the exact vulnerable versions.
How do I fix CVE-2025-3859?: Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround.
Does CVE-2025-3859 have an EU (EUVD) identifier?: Yes. CVE-2025-3859 is tracked in the ENISA EU Vulnerability Database (EUVD) as EUVD-2025-12733.
When was CVE-2025-3859 published?: CVE-2025-3859 was published on 2025-04-30 and last updated on 2026-06-17.

References

Affected products (1)

cpe:2.3:a:mozilla:firefox_focus:*:*:*:*:*:iphone_os:*:*

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