CVE-2026-31873: Improper Neutralization of Input During Web Page Generation

Unhead is a document head and template manager. Prior to 2.1.11, The link.href check in makeTagSafe safe.ts uses String.includes, which is case-sensitive. Browsers treat URI schemes case-insensitively. DATA:text/css,... is the same as data:text/css,... to the browser, but 'DATA:...'.includes'data...