A flaw in Node.js TLS hostname verification allows a certificate without a matching IP address SAN to authenticate a connection to an IPv4 address when the host is written with non-ASCII characters, such as fullwidth digits (`１２７.0.0.1`). `tls.checkServerIdentity()` did not recognize such hosts as IP addresses, even though they normalize and resolve to a regular IPv4 address, and matched them against the certificate DNS names and Common Name instead. A certificate containing `DNS:127.0.0.1` or `DNS:*.0.0.1` could therefore be accepted for an IP endpoint it was not issued for. This is a regression introduced after the fix for CVE-2026-48618. This vulnerability affects Node.js 26.x and 24.x.

HighVendor CVSS 7.4 / 10 2 CVEs Published Oct 25, 2026 at 1:01 AM UTC

Summary

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Release Notes

Oct 25, 2026 at 1:01 AM UTC
Published by Microsoft Security Response Center
The publication date reported by the vendor.
Oct 26, 2026 at 2:50 PM UTC
Updated by Microsoft Security Response Center
The vendor changed the advisory after it was first published.
Oct 27, 2026 at 9:20 AM UTC
Added to SecurityAlert
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Oct 27, 2026 at 9:40 PM UTC
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Details collected from Microsoft Security Response Center.

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