How severe is CVE-2026-44658?

CVE-2026-44658 has a CVSS 3.x base score of 2.4, rated low severity. It is exploitable over network with low attack complexity, requires high privileges and user interaction. Impact on confidentiality is none, integrity low, and availability none.

Is CVE-2026-44658 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 0% (5th percentile), an estimate of the probability of exploitation in the next 30 days.

How do I fix CVE-2026-44658?

Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround.

Does CVE-2026-44658 have an EU (EUVD) identifier?

Yes. CVE-2026-44658 is tracked in the ENISA EU Vulnerability Database (EUVD) as EUVD-2026-29132.

When was CVE-2026-44658 published?

CVE-2026-44658 was published on 2026-05-11 and last updated on 2026-06-17.

CVE-2026-44658

CVE-2026-44658 is a low-severity vulnerability with a CVSS 3.x base score of 2.4. It is not currently listed as actively exploited by CISA, and its EPSS exploit-prediction score is low. The underlying weakness is classified as CWE-20.

Key facts

Severity: Low (CVSS 3.x base score 2.4)
EPSS exploit prediction: 0% (5th percentile)
Actively exploited: Not listed in CISA KEV
EU (EUVD) id: EUVD-2026-29132
Weakness: CWE-20
Published: 2026-05-11
Last modified: 2026-06-17

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.

Frequently asked questions

What is CVE-2026-44658?: 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.
How severe is CVE-2026-44658?: CVE-2026-44658 has a CVSS 3.x base score of 2.4, rated low severity. It is exploitable over network with low attack complexity, requires high privileges and user interaction. Impact on confidentiality is none, integrity low, and availability none.
Is CVE-2026-44658 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 0% (5th percentile), an estimate of the probability of exploitation in the next 30 days.
How do I fix CVE-2026-44658?: Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround.
Does CVE-2026-44658 have an EU (EUVD) identifier?: Yes. CVE-2026-44658 is tracked in the ENISA EU Vulnerability Database (EUVD) as EUVD-2026-29132.
When was CVE-2026-44658 published?: CVE-2026-44658 was published on 2026-05-11 and last updated on 2026-06-17.

References

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

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