Bypass of meta content URL escaping causes XSS in html/template

GO-2026-4982 · BIT-golang-2026-39823 · CVE-2026-39823

Published May 7, 2026 · Modified May 11, 2026

Description

CVE-2026-27142 fixed a vulnerability in which URLs were not correctly escaped inside of a tag's attribute. If the URL content were to insert ASCII whitespaces around the '=' rune inside of the attribute, the escaper would fail to similarly escape it, leading to XSS.

References

REPORT https://go.dev/issue/78913
FIX https://go.dev/cl/769920
WEB https://groups.google.com/g/golang-announce/c/qcCIEXso47M

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