security: restrict link and update-banner URLs to safe schemes#59
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Two places trusted a URL more than they should: - normalizeHref (Cmd+K link mark) passed through any explicit scheme, so javascript: and data: could be persisted into the saved .md and later clicked — a stored script-execution vector in a shared document. It now allows only http/https/mailto/tel (plus in-page and relative refs); any other scheme returns empty. - The update banner's "View release" button opened the html_url from GitHub's API response verbatim. It now accepts that URL only if it parses as an https://github.com/ URL, falling back to the hardcoded releases page otherwise, so a spoofed or compromised response can't redirect the user to an arbitrary scheme or host. Adds coverage for the rejected schemes (javascript/data/vbscript/file) and for html_url fallback on a dangerous scheme and a non-github host. Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
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Jun 13, 2026
Documents Quill's security posture for a reviewing engineer: the threat model (deep link as the one attacker-influenced entry point; deserialized data trusted more than rendered data), the four merged hardening measures (#57 path confinement + deep-link validation, #58 annotation sanitization, #59 URL scheme allowlists, #60 binary-resolution hardening), and the two deliberate non-fixes left in place with rationale (asset-protocol $HOME/** scope, remote-image beacon). Co-authored-by: Claude Opus 4.8 <noreply@anthropic.com>
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What
Two places trusted a URL more than they should.
normalizeHref(the Cmd+K link mark) passed through any explicit scheme, sojavascript:anddata:could be persisted into the saved.mdand later clicked — a stored script-execution vector in a shared document. It now allows onlyhttp/https/mailto/tel(plus in-page and relative refs); any other scheme returns empty.html_urlfrom GitHub's API response verbatim. It now accepts that URL only if it parses as anhttps://github.com/URL, falling back to the hardcoded releases page otherwise — a spoofed or compromised response can't redirect the user to an arbitrary scheme or host.Tests
Added coverage for the rejected link schemes (
javascript/data/vbscript/file, case-insensitive) and forhtml_urlfallback on both a dangerous scheme and a non-github host. Full bar green: typecheck, eslint, prettier, vitest (235).🤖 Generated with Claude Code