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Fencer Vulns
medium 4.6

CVE-2021-40835 json

URL Address Bar Spoofing in F-Secure SAFE Browser for iOS

published 2021-12-16 4 y ago modified 2026-06-17 4 mo ago also EUVD-2021-27992

cvss
4.6
version 3.1, CNA
cisa kev
Not listed
not in CISA's catalog
epss
0.7%
EPSS 0.7% chance of exploitation in 30 days, percentile 54%
public exploits
0
none known

Summary

An URL Address bar spoofing vulnerability was discovered in Safe Browser for iOS. When user clicks on a specially crafted a malicious URL, if user does not carefully pay attention to url, user may be tricked to think content may be coming from a valid domain, while it comes from another. This is performed by using a very long username part of the url so that user cannot see the domain name. A remote attacker can leverage this to perform url address bar spoofing attack. The fix is, browser no longer shows the user name part in address bar.

Patch / fix

  • F-Secure F-Secure Mobile Security 18.5

Exploit prediction

0.73% chance of exploitation in the next 30 days, higher than 54% of all scored CVEs (FIRST EPSS, 2026-11-08).

CVSS scores

assigned by version score vector
CNA 3.1 4.6 CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:U/C:L/I:L/A:N
NVD 3.1 4.3 CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:L/A:N
NVD 2.0 4.3 AV:N/AC:M/Au:N/C:N/I:P/A:N

Affected products

  • F-Secure F-Secure Mobile Security

References

Sources

Fencer Vulns keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.