# CVE-2026-44658: Zen Browser Improper Input Validation in RSS Live-Folders

Source: https://junglewise.ai/threats/cve-2026-44658-zen-browser-improper-input-validation-in-rss-live-folders  
Publisher: Junglewise Threat Intelligence, https://junglewise.ai/threats  
Published: 2026-05-11. Updated: 2026-05-11  
License: CC BY 4.0 with a link back

CVE-2026-44658 · Severity: low · CVSS 2.4 · Published 2026-05-11

Zen Browser, a web browser based on Firefox, contains a vulnerability in how it handles RSS feeds. While the browser checks that the main feed address is a standard web link, it fails to verify the individual links within that feed. This could allow a malicious or compromised RSS feed to force the browser to open tabs using restricted or dangerous internal addresses, potentially leading to unauthorized actions within the browser interface.

Technologies: [Zen Browser](https://junglewise.ai/threats/technologies/zen-browser). Vendors: [Zen Browser](https://junglewise.ai/threats/vendors/zen-browser).

## Quick answers

**Is CVE-2026-44658 exploited in the wild?** No. Junglewise Threat Intelligence has no report of CVE-2026-44658 being exploited in the wild.

**How severe is CVE-2026-44658?** Low severity, with a CVSS score of 2.4, published 11 May 2026.

**Which products and versions are affected?** Zen Browser < 1.19.12b.

**Is there a fix for CVE-2026-44658?** A patch was published on 2026-05-11: Vulnerability fixed in version 1.19.12b Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.

**How is CVE-2026-44658 attacked?** It is attacked over the network, in a network appliance.

**Am I affected by CVE-2026-44658?** Check whether you run Zen Browser at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

## Technical details

A vulnerability exists in Zen Browser's RSS live-folder manager where item links within a feed are not restricted to http or https schemes. While the top-level feed URL is validated in promptForFeedUrl, individual item.url values are mapped and passed directly to gBrowser.addTrustedTab() without further validation. An attacker who controls an RSS feed can include items with non-web schemes (such as file:, chrome:, or about:). If a user adds this feed, the browser will create pinned lazy tabs for these items, potentially bypassing security boundaries intended for ordinary web content. This issue is resolved in version 1.19.12b by implementing scheme validation for all item URLs.

## Affected products

- Zen Browser Zen Browser < 1.19.12b

## Timeline

- 2026-05-08: advisory: GitHub security advisory published
- 2026-05-11: disclosed: CVE published to NVD
- 2026-05-11: patched: Vulnerability fixed in version 1.19.12b

## References

- [https://github.com/zen-browser/desktop/security/advisories/GHSA-cc9c-mmmf-c5j6](https://github.com/zen-browser/desktop/security/advisories/GHSA-cc9c-mmmf-c5j6)

## Related threats

- [Zen Browser UI misrepresentation in fullscreen mode](https://junglewise.ai/threats/cve-2026-45150-zen-browser-ui-misrepresentation-in-fullscreen-mode)
- [Zen Browser Privilege Escalation in Glance and Split-View Context Menus](https://junglewise.ai/threats/cve-2026-57501-zen-browser-privilege-escalation-in-glance-and-split-view-context)
- [Zen Browser address bar spoofing via long subdomains](https://junglewise.ai/threats/cve-2026-44659-zen-browser-address-bar-spoofing-via-long-subdomains)
- [Zen Browser improper signature verification in MAR updater](https://junglewise.ai/threats/cve-2026-41431-zen-browser-improper-signature-verification-in-mar-updater)