# CVE-2026-44658: Zen Browser: RSS Live-Folder Item URLs Are Not Scheme-Restricted Before Trusted Tab Creation

> Attackers can execute arbitrary code or bypass security controls by crafting RSS feeds with malicious item URLs that bypass scheme restrictions in Zen Browser.

- **Severity:** Low 2.4 (`CVSS:3.1/AV:N/AC:L/PR:H/UI:R/S:U/C:N/I:L/A:N`)
- **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:** 11 May 2026
- **Updated:** 11 May 2026
- **Also known as:** GHSA-cc9c-mmmf-c5j6

## What is CVE-2026-44658?

CVE-2026-44658 is a low-severity vulnerability in zen-browser desktop, published on 11 May 2026. An attacker needs administrator access to exploit it, and only if a user opens a file or follows a link.

### Official description

Zen is a firefox-based browser. Prior to 1.19.12b, RSS feed URLs entered by the user are validated to http: or https: in promptForFeedUrl, but item links inside the feed are not subject to the same restriction. The provider maps each RSS/Atom item link into item.url, filters only for presence and date, and returns the item list. The live-folder manager later creates pinned lazy tabs from these values with gBrowser.addTrustedTab(item.url, ...). This vulnerability is fixed in 1.19.12b.

Weakness: CWE-20 (Improper Input Validation)

## Which versions are affected by CVE-2026-44658?


## How do I fix CVE-2026-44658?

No fix has been published for CVE-2026-44658 yet. Limit exposure of the affected software until one is available.

## Is CVE-2026-44658 being exploited?

There is no known exploitation of CVE-2026-44658 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-44658 and fix it if it is affected.

What it is: CVE-2026-44658 is a low-severity vulnerability in zen-browser desktop, published on 11 May 2026. 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-2026-44658 in the wild and no public exploit code.

Affected product: zen-browser desktop. 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-2026-44658/ (Markdown: https://insights.sbomify.com/CVE-2026-44658/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-44658
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-44658
- OSV: https://osv.dev/vulnerability/CVE-2026-44658

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-44658/
Summaries are generated and may contain mistakes; the official description above is the record.