URL previews are built from the plain body, but clicks follow formatted_body's hrefs, and a sender controls both. A link whose text reads https://paypal.com but points to https://evil.example/login was caught by the click confirmation (#122), yet the message still showed a genuine PayPal preview card.
Change: new previewUrlsFor(urls, formattedBody). It runs every <a> in formatted_body through analyzeLink, and drops any body URL whose site is only claimed by a mismatched link's text. Honest links and other URLs in the same message keep their previews. It's used by all three message renderers (text, notice, emote).
Verified (Chromium, preview fixture for PayPal; Bob sends pay here <a href="https://evil.example/login">https://paypal.com</a>):
Before: the PayPal card shows.
After: no card.
Unit tests: deceptive → no preview; honest link (www.paypal.com) → preview; no HTML → unchanged; mixed message → only the deceptive one dropped.
Fixes #286.
URL previews are built from the plain `body`, but clicks follow `formatted_body`'s `href`s, and a sender controls both. A link whose text reads `https://paypal.com` but points to `https://evil.example/login` was caught by the click confirmation (#122), yet the message still showed a **genuine PayPal preview card**.
**Change:** new `previewUrlsFor(urls, formattedBody)`. It runs every `<a>` in `formatted_body` through `analyzeLink`, and drops any body URL whose site is only **claimed** by a mismatched link's text. Honest links and other URLs in the same message keep their previews. It's used by all three message renderers (text, notice, emote).
**Verified** (Chromium, preview fixture for PayPal; Bob sends `pay here <a href="https://evil.example/login">https://paypal.com</a>`):
- **Before:** the PayPal card shows.
- **After:** no card.
Unit tests: deceptive → no preview; honest link (www.paypal.com) → preview; no HTML → unchanged; mixed message → only the deceptive one dropped.
`tsc` clean · unit tests pass · ESLint clean.
🤖 Generated with [Claude Code](https://claude.com/claude-code)
https://claude.ai/code/session_017PCb59uY3UKqDqt7B6hzd5
Previews are built from the plain body, clicks follow formatted_body's
hrefs, and a sender controls both: text "https://paypal.com" linked to
evil.example showed a real PayPal card. Drop body URLs whose site is
only claimed by the visible text of a mismatched link (linkSafety).
Fixes#286
Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_017PCb59uY3UKqDqt7B6hzd5
jared
merged commit 8a3b2eeb61 into lotus2026-10-18 06:15:47 -04:00
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Fixes #286.
URL previews are built from the plain
body, but clicks followformatted_body'shrefs, and a sender controls both. A link whose text readshttps://paypal.combut points tohttps://evil.example/loginwas caught by the click confirmation (#122), yet the message still showed a genuine PayPal preview card.Change: new
previewUrlsFor(urls, formattedBody). It runs every<a>informatted_bodythroughanalyzeLink, and drops any body URL whose site is only claimed by a mismatched link's text. Honest links and other URLs in the same message keep their previews. It's used by all three message renderers (text, notice, emote).Verified (Chromium, preview fixture for PayPal; Bob sends
pay here <a href="https://evil.example/login">https://paypal.com</a>):Unit tests: deceptive → no preview; honest link (www.paypal.com) → preview; no HTML → unchanged; mixed message → only the deceptive one dropped.
tscclean · unit tests pass · ESLint clean.🤖 Generated with Claude Code
https://claude.ai/code/session_017PCb59uY3UKqDqt7B6hzd5