CVE-2021-33596Network attack vector

Trusted-origin spoofing via embedded malicious redirect

Published Aug 5, 2021 · Updated Aug 3, 2024

URL spoofing in F-Secure Mobile Security SAFE Browser 18.3x and earlier allows remote authenticated users to show content under a trusted address. A crafted URL embeds a malicious redirect that loads content from another domain while the address bar continues to display the legitimate URL. A user must click the crafted link, allowing the false origin display to support credential-phishing content without direct data access.

CVSS severity3.5
Low
EPSS probability0.80%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

URL spoofing in F-Secure Mobile Security SAFE Browser 18.3x and earlier allows remote authenticated users to show content under a trusted address. A crafted URL embeds a malicious redirect that loads content from another domain while the address bar continues to display the legitimate URL. A user must click the crafted link, allowing the false origin display to support credential-phishing content without direct data access.

The record

CVE
CVE-2021-33596
Published
Aug 5, 2021
Updated
Aug 3, 2024
Vendor
F-Secure
Product
F-Secure Mobile Security
Classifications
CWE-1021, T1566.002
Attack vector
network
Privileges
authenticated

Timeline

How it unfolded

  1. Aug 5, 2021CVE publishedPublication date reported by the CVE source.
  2. Aug 3, 2024Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=18.3x <18.4x

What conditions does exploitation require?

Attack vectornetwork
Required privilegesauthenticated

What is affected?

F-Secure · F-Secure Mobile Securityversion=18.3x <18.4x

Published CVSS scores

3.5F-SecureCVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:U/C:N/I:L/A:N
4.1NIST NVDCVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:N/I:L/A:N
3.5NIST NVDAV:N/AC:M/Au:S/C:N/I:P/A:N

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-1021Improper Restriction of Rendered UI Layers or Frames
T1566.002Phishing: Spearphishing Link

Public exploit references

No public exploit references are available in this record.

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

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Your stack

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