Firefox Focus elide URL allows address bar spoofing

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Summary

CVECVE-2025-3859
StatePUBLISHED
Assignermozilla
Source PriorityCVE Program / NVD first with legacy fallback
Published2025-04-30 17:15:50 UTC
Updated2026-04-13 15:16:58 UTC
DescriptionWebsites 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.

Risk And Classification

Primary CVSS: v3.1 6.1 MEDIUM from [email protected]

CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N

EPSS: 0.001560000 probability, percentile 0.364530000 (date 2026-04-15)

Problem Types: CWE-601 | CWE-451 | CWE-451 CWE-451 User Interface (UI) Misrepresentation of Critical Information

VersionSourceTypeScoreSeverityVector
3.1[email protected]Primary6.1MEDIUMCVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N
3.1ADPDECLARED4.3MEDIUMCVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:L/I:N/A:N
3.1134c704f-9b21-4f2e-91b3-4a467353bcc0Secondary4.3MEDIUMCVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:L/I:N/A:N

CVSS v3.1 Breakdown

Attack Vector
Network
Attack Complexity
Low
Privileges Required
None
User Interaction
Required
Scope
Changed
Confidentiality
Low
Integrity
Low
Availability
None

CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N

NVD Known Affected Configurations (CPE 2.3)

TypeVendorProductVersionUpdateEditionLanguage
Application Mozilla Firefox Focus All All All All

Vendor Declared Affected Products

SourceVendorProductVersionPlatforms
CNA Mozilla Focus unaffected 138 * rpm Not specified

References

ReferenceSourceLinkTags
bugzilla.mozilla.org/show_bug.cgi [email protected] bugzilla.mozilla.org Issue Tracking
www.mozilla.org/security/advisories/mfsa2025-33 [email protected] www.mozilla.org Vendor Advisory
CVE Program record CVE.ORG www.cve.org canonical
NVD vulnerability detail NVD nvd.nist.gov canonical, analysis

Vendor Comments And Credit

Discovery Credit

CNA: James Lee (en)

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