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CVE-2026-44658

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

Published: May 11, 2026Updated: May 13, 2026 Sources: CVE List NVDCWE-20
NVD MITRE
2.4CVSSLOW
EPSS Score
0.2%
Top 94.8%
CISA KEV
Not in KEV
Exploits
No Known Exploits
Remediation
No Fix Available

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.

CVSS Vector Breakdown

AV:NAC:LPR:HUI:RS:UC:NI:LA:N
Exploitability
AV:NAttack Vector
Network
AC:LAttack Complexity
Low
PR:HPrivileges Required
High
UI:RUser Interaction
Required
Scope
S:UScope
Unchanged
Impact
C:NConfidentiality
None
I:LIntegrity
Low
A:NAvailability
None
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Weaknesses

CWE-20

Affected Products

desktopzen-browser
Mixed
Consumer Software / browser
zen-browseross-projectConsumer Softwareaka desktop

Attack Graph

Products CVE Techniques Tactics

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Exploitability

No known exploits, KEV entries, or remediation guidance available for this vulnerability yet.

MITRE ATT&CK

1 technique
Initial Access
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References

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

Timeline

Published
May 11, 2026
Last Updated
May 13, 2026

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