Vulnerability in Fenrir Sleipnir Mobile For Android
CVE-2026-109434
Fenrir Sleipnir Browser for Android before 3.9.0 contains a UI spoofing vulnerability that allows remote attackers to impersonate the browser's trusted address bar by entering fullscreen mode via the Fullscreen API without displaying a persistent notification or trusted-origin indicator. Attackers can render a counterfeit address bar showing a trusted origin over attacker-controlled content after a single user tap, enabling credential harvesting, malware delivery, or social engineering through fake login, update, or payment pages.
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
No EPSS score from FIRST.org yet. New CVEs usually get one within a few days; no score means no signal yet, not low risk. How EPSS works.
Affected products
Weakness classification (CWE)
References
- www.fenrir-inc.com/jp/news/2026/10/15/sleipnir-mobile-for-android-3-9-0/ (vendor-advisory, patch)
- www.vulncheck.com/advisories/sleipnir-browser-fullscreen-address-bar-spoofing (third-party-advisory)
Frequently asked questions
- What is CVE-2026-109434?
- CVE-2026-109434 is a medium-severity vulnerability in Fenrir Sleipnir Mobile For Android, classified under User Interface (UI) Misrepresentation of Critical Information. CVSS score: 4.3/10. Published 2026-10-19.
- How severe is CVE-2026-109434?
- Medium severity. CVSS v3 base score is 4.3 out of 10.