# CVE-2021-40835: URL Address Bar Spoofing in F-Secure SAFE Browser for iOS

> Attackers can spoof the URL address bar in F-Secure SAFE Browser for iOS by hiding the domain behind a long username, tricking users into trusting malicious sites.

- **Severity:** Medium 4.6 (`CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:U/C:L/I:L/A:N`)
- **Exploited in the wild:** Not known
- **Login needed:** Any signed-in user
- **Attackable:** Over the internet
- **Victim action needed:** A user has to click or open something
- **Fix available:** No
- **Published:** 16 Dec 2021
- **Updated:** 4 Aug 2024
- **Also known as:** GHSA-75cm-2vvh-47g6

## What is CVE-2021-40835?

CVE-2021-40835 is a medium-severity vulnerability in F-Secure Mobile Security, published on 16 Dec 2021. Any signed-in user can exploit it over the network, and only if a user opens a file or follows a link.

### Official description

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.

## Which versions are affected by CVE-2021-40835?

It affects 1 product.


Products: F-Secure Safe.

## How do I fix CVE-2021-40835?

No fix has been published for CVE-2021-40835 yet. Limit exposure of the affected software until one is available.

## Is CVE-2021-40835 being exploited?

There is no known exploitation of CVE-2021-40835 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-2021-40835 and fix it if it is affected.

What it is: CVE-2021-40835 is a medium-severity vulnerability in F-Secure Mobile Security, published on 16 Dec 2021. Any signed-in user can exploit it over the network, and only if a user opens a file or follows a link.
Exploitation: There is no known exploitation of CVE-2021-40835 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-2021-40835/ (Markdown: https://insights.sbomify.com/CVE-2021-40835/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2021-40835
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2021-40835
- OSV: https://osv.dev/vulnerability/CVE-2021-40835

---
From sbomify Insights: https://insights.sbomify.com/CVE-2021-40835/
Summaries are generated and may contain mistakes; the official description above is the record.