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NVD / CVE Program· CNA GitHub_M

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

LowCVSS 2.4 · v3.1—No exploit Fix available

Noroxi assessment

Priority: Monitor (action score 9/100)

  • The sources we track (CISA KEV, Exploit-DB, Metasploit, Nuclei, GitHub) show no public exploit code or exploitation in the wild.
  • Probability of exploitation in the next 30 days: 0.15% (FIRST EPSS).
  • Anyone who can reach it over the internet can trigger it. Administrator privileges are required. A user must open a link or visit a page. No special conditions are required; it is repeatable.
  • Fixed version: zen-browser desktop 1.19.12b.

Low priority for now. Upgrade to zen-browser desktop 1.19.12b or later.

Generated automatically from the record's data: CVSS (NVD and CNA), CISA KEV and SSVC, FIRST EPSS, exploit sources, fixed versions. How we calculate it

Primary sources: NVD · CVE.org · FIRST EPSS

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.

Published
May 11, 2026
Updated
Oct 26, 2026
EPSS
0.1% · 4th percentile

Report tools

JSON

Action score

9

Monitor

Low priority for now.

CVSS
9 / 40 · 2.4 / 10
CISA KEV
0 / 30 · Not listed
EPSS
0 / 30 · 0.1%

CISA SSVC decision

Exploitation
none
Automatable
no
Technical impact
partial

Vulnrichment: CISA's decision-tree inputs.

CNA vs NVD score

NVD
—
CNA · GitHub_M
2.4
NVD has not scored this yet; the score shown is the CNA’s.

The score given by the assigning authority versus NVD’s independent score. A gap means the severity is contested.

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  • Not in KEV: no record of exploitation in the wild
  • No public exploit code on record
  • A fix has been released

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Follow CVE-2026-44658

When you'll hear from us

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  • when exploit code appears or is weaponized
  • when the record is updated (including a fixed version)
  • when EPSS rises 20 points in a week

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Noroxi analysis

What does it mean in your environment?

The assessment above is generated automatically from the record's data; it doesn't know your environment. Our team verifies on your systems whether this vulnerability is actually exploitable and which mitigation is enough.

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Affected systems

Is your version affected?

Pick the product and type the version you run. It's compared with this record's version ranges in your browser; the version isn't sent anywhere.

—

Versions reported by the vendor

Affected version ranges reported by the assigning authority (GitHub_M). Independent of NVD's CPE analysis and usually ahead of it.

  • zen-browser desktop

    • < 1.19.12baffected

Same product

zen-browser: all records

Other highest-scoring records for the same primary product.

  • CVE-2026-41431Zen Browser MAR updater ships with signature verification removed — unsigned updates accepted
    32Monitor
  • CVE-2026-45150Zen Browser - Missing Fullscreen Security Notification Allows Origin Spoofing
    25Monitor
  • CVE-2026-44659Zen Browser Mac - Address Bar Spoofing via Long Subdomain
    18Monitor

Published before and after this one in the same product

  • Later →CVE-2026-57501Jul 9, 2026 · Zen: Context-menu "Open link in glance" / "Split link in new tab" loads a page-controlled link with the System principal, bypassing the web-content scheme…
    0Monitor

Remediation

Which version to upgrade to

Fix versions compiled from the vendor, package registries and Microsoft. Verify the vendor's note before upgrading.

Product / packageFixed versionSource
zen-browser desktop1.19.12b · descriptionVendor (CNA)

Exploit status

No known public exploit

No public exploit has been observed yet. That doesn't mean you're safe, only that the bar is a little higher.

Research context

For pentesters and researchers: attack profile, score disagreement, timeline, patch commits, credits, variant and chain candidates, bug bounty scope. All derived from existing data; no exploit code.

Timeline

From publication to today: proof of concept, Metasploit module, CISA KEV and fix record. Dates are as reported by the sources.

No dated events beyond publication.

Not on record for this CVE: EPSS history · patch commit or PR link · researcher credit · variant or chain candidate · public bounty program.

Technical details

Attack conditions

  • Anyone who can reach it over the internet can trigger it.
  • Administrator privileges are required.
  • A user must open a link or visit a page.
  • No special conditions are required; it is repeatable.

If successful

Confidentiality
none
Integrity
low · data or configuration can be modified
Availability
none
Attack vector
Network
Attack complexity
Low
Privileges required
High
User interaction
Required
Scope
Unchanged
Confidentiality impact
None
Integrity impact
Low
Availability impact
None

Weakness class (CWE)

CWE-20 · Improper Input Validation

CVSS vector

CVSS:3.1/AV:N/AC:L/PR:H/UI:R/S:U/C:N/I:L/A:N

nvd-secondary

Attack context

MITRE CAPEC attack patterns and ATT&CK techniques for this weakness class (CWE). A starting point for detection rules and threat hunting.

References

Vendor advisories and official records. Exploit/PoC links are deliberately left out.

All records