CVE-2026-44658: Input Validation Flaw (CVSS 2.4)

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.

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CVSS v3.1 Score

2.4

LOW

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

EPSS — Exploit Prediction

0.0004

Probability of exploitation

0.14%

Percentile rank

EPSS estimates the probability that this vulnerability will be exploited in the wild within the next 30 days. A higher score means more likely to be exploited.

Weakness Type (CWE)

CWE-20 Improper Input Validation

References

Other References

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

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. It has a CVSS v3.1 base score of 2.4 (LOW).

How severe is CVE-2026-44658? +

CVE-2026-44658 has a CVSS v3.1 score of 2.4 out of 10, rated LOW. This is a low-severity vulnerability with limited impact. The EPSS score is 0.0004, placing it in the 0th percentile for exploitation probability.

How do I check if I'm vulnerable to CVE-2026-44658? +

You can use Secably's free Website Scanner to check your website for known vulnerabilities. For infrastructure scanning, use the Port Scanner to identify exposed services that may be affected. Check the vendor advisories linked above for specific patch and version information.

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