Mozilla Releases Firefox 158.0.1 Security Update Fixing High-Severity Vulnerabilities and Compromised Certificates

Mozilla Foundation has published Firefox 158.0.1 on October 20, 2026, delivering fixes for four CVEs rated at high overall severity. Two vulnerabilities received a High rating, including a boundary condition flaw in the SVG component tracked as CVE-2026-113399 and a certificate blocklist issue identified as CVE-2026-113470. The update also refreshes the OneCRL list to block an intermediate certificate from eMudhra that was compromised earlier in the month. Mozilla delivered the updated blocklist via RemoteSettings on October 17 and embedded the changes directly into the browser release. This approach ensures compromised certificates remain blocked even when RemoteSettings is disabled or network access is unavailable. One Moderate and one Low severity issue complete the set of addressed flaws.

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Mozilla Foundation has released the security update Firefox 158.0.1 on October 20, 2026, addressing multiple vulnerabilities and updating protections against a compromised intermediate certificate.

The release carries an overall importance rating of High and resolves four CVEs. Two issues are rated High, one Moderate, and one Low.

The High-severity flaws include a boundary condition vulnerability in the SVG component tracked as CVE-2026-113399 and a certificate blocklist problem identified as CVE-2026-113470.

For CVE-2026-113470, Mozilla responded to the compromise of an eMudhra intermediate certificate by updating the OneCRL blocklist on October 17. The updated list was distributed the same day through RemoteSettings.

The new browser version ensures that compromised certificates are blocked even if RemoteSettings is disabled or unavailable due to network restrictions.

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