# CVE-2021-40834: User interface Spoofing in F-Secure SAFE browser for Android

> Remote attackers can spoof the user interface by hiding browser controls via full-screen mode, misleading users about the current page context.

- **Severity:** Medium 4.3 (`CVSS:3.1/AV:N/AC:L/PR:H/UI:R/S:U/C:L/I:L/A:L`)
- **Exploited in the wild:** Not known
- **Login needed:** An administrator
- **Attackable:** Over the internet
- **Victim action needed:** A user has to click or open something
- **Fix available:** No
- **Published:** 10 Dec 2021
- **Updated:** 4 Aug 2024
- **Also known as:** GHSA-39jf-9gqp-rjmj

## What is CVE-2021-40834?

CVE-2021-40834 is a medium-severity vulnerability in F-Secure Mobile Security, published on 10 Dec 2021. An attacker needs administrator access to exploit it, and only if a user opens a file or follows a link.

### Official description

A user interface overlay vulnerability was discovered in F-secure SAFE Browser for Android. When user click on a specially crafted seemingly legitimate URL SAFE browser goes into full screen and hides the user interface. A remote attacker can leverage this to perform spoofing attack.

Weakness: CWE-1021 (Improper Restriction of Rendered UI Layers or Frames)

## Which versions are affected by CVE-2021-40834?

It affects 1 product.


Products: F-Secure Safe.

## How do I fix CVE-2021-40834?

No fix has been published for CVE-2021-40834 yet. Limit exposure of the affected software until one is available.

## Is CVE-2021-40834 being exploited?

There is no known exploitation of CVE-2021-40834 in the wild and no public exploit code.

## Other vulnerabilities in F-Secure Mobile Security

- [CVE-2020-14977](https://insights.sbomify.com/CVE-2020-14977/): Race condition in n/a (high 8.1)
- [CVE-2020-14978](https://insights.sbomify.com/CVE-2020-14978/): Privilege escalation in n/a (high 8.1)
- [CVE-2022-38164](https://insights.sbomify.com/CVE-2022-38164/): Security feature bypass in n/a (medium 6.5)
- [CVE-2021-44748](https://insights.sbomify.com/CVE-2021-44748/): Universal Cross-Site Scripting Vulnerability in F-Secure SAFE Browser for Android (medium 5.5)
- [CVE-2021-44749](https://insights.sbomify.com/CVE-2021-44749/): Universal Cross-Site Scripting Vulnerability in F-Secure SAFE Browser Protection for Android (medium 5.5)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2021-40834 and fix it if it is affected.

What it is: CVE-2021-40834 is a medium-severity vulnerability in F-Secure Mobile Security, published on 10 Dec 2021. An attacker needs administrator access to exploit it, and only if a user opens a file or follows a link.
Exploitation: There is no known exploitation of CVE-2021-40834 in the wild and no public exploit code.

Affected product: F-Secure Mobile Security. No package-level version data is available, so check the vendor advisory linked from the reference page.

Task:
1. Search the dependency manifests and lockfiles (for example package.json, package-lock.json, requirements.txt, poetry.lock, uv.lock, pom.xml, build.gradle, go.mod, Cargo.lock, Gemfile.lock) and any Dockerfiles for the affected packages, including transitive dependencies.
2. If an affected version is in use, upgrade it to the fixed version for its release line with the project's package manager, so the lockfile is regenerated. Prefer the smallest upgrade that fixes it.
3. If there is no fix, or the upgrade would break the build, do not guess: explain the risk and the safest workaround instead.
4. Run the tests and summarise what changed and why.
5. If nothing in the project is affected, say so and change nothing.

Reference: https://insights.sbomify.com/CVE-2021-40834/ (Markdown: https://insights.sbomify.com/CVE-2021-40834/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2021-40834
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2021-40834
- OSV: https://osv.dev/vulnerability/CVE-2021-40834

---
From sbomify Insights: https://insights.sbomify.com/CVE-2021-40834/
Summaries are generated and may contain mistakes; the official description above is the record.