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fix: DNS rebinding protection checks AAAA (IPv6) records too#744

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Gonzih:fix/dns-rebinding-ipv6-aaaa
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fix: DNS rebinding protection checks AAAA (IPv6) records too#744
Gonzih wants to merge 1 commit intogarrytan:mainfrom
Gonzih:fix/dns-rebinding-ipv6-aaaa

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@Gonzih Gonzih commented Apr 1, 2026

The Gap

`resolvesToBlockedIp()` in `url-validation.ts` only called `resolve4()` (A records). A DNS rebinding attack using AAAA-only records pointing to IPv6 metadata endpoints (e.g. `fe80::1`, GCP's IPv6 metadata endpoint) bypassed the check completely.

Issue #668 documented this. Here's the fix.

Changes

  • Check both `resolve4` and `resolve6` in parallel via `Promise.all`
  • Block the entire `fe80::/10` link-local range (not just one address)
  • Add `::ffff:169.254.169.254` (IPv4-mapped IPv6) to the blocklist
  • Each record family handles its own errors — `ENODATA` on AAAA doesn't suppress the A record check

The DNS calls were already async and run in parallel, so no performance regression.


sent from mStack

resolvesToBlockedIp() was only calling resolve4() — an attacker could
host a DNS entry with only AAAA records pointing to a blocked IPv6
metadata endpoint (fe80::, fd00::, etc.) and bypass the check entirely.

Fix:
- Check both A and AAAA records in parallel (Promise.all)
- Block entire fe80::/10 link-local range, not just a single address
- Add ::ffff:169.254.169.254 (IPv4-mapped IPv6) to the blocklist
- Independent error handling per record family — ENODATA on one type
  doesn't suppress the other

Closes garrytan#668
garrytan added a commit that referenced this pull request Apr 5, 2026
Cherry-pick PR #744 by @Gonzih. Closes the IPv6-only DNS rebinding gap
by checking both A and AAAA records independently.

Co-Authored-By: Gonzih <gonzih@users.noreply.github.com>
Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>
garrytan added a commit that referenced this pull request Apr 5, 2026
* fix: DNS rebinding protection checks AAAA (IPv6) records too

Cherry-pick PR #744 by @Gonzih. Closes the IPv6-only DNS rebinding gap
by checking both A and AAAA records independently.

Co-Authored-By: Gonzih <gonzih@users.noreply.github.com>
Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

* fix: validateOutputPath symlink bypass — resolve real path before safe-dir check

Cherry-pick PR #745 by @Gonzih. Adds a second pass using fs.realpathSync()
to resolve symlinks after lexical path validation.

Co-Authored-By: Gonzih <gonzih@users.noreply.github.com>
Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

* fix: validate saved URLs before navigation in restoreState

Cherry-pick PR #751 by @Gonzih. Prevents navigation to cloud metadata
endpoints or file:// URIs embedded in user-writable state files.

Co-Authored-By: Gonzih <gonzih@users.noreply.github.com>
Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

* fix: telemetry-ingest uses anon key instead of service role key

Cherry-pick PR #750 by @Gonzih. The service role key bypasses RLS and
grants unrestricted database access — anon key + RLS is the right model
for a public telemetry endpoint.

Co-Authored-By: Gonzih <gonzih@users.noreply.github.com>
Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

* fix: killAgent() actually kills the sidebar claude subprocess

Cherry-pick PR #743 by @Gonzih. Implements cross-process kill signaling
via kill-file + polling pattern, tracks active processes per-tab.

Co-Authored-By: Gonzih <gonzih@users.noreply.github.com>
Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

* fix(design): bind server to localhost and validate reload paths

Cherry-pick PR #803 by @garagon. Adds hostname: '127.0.0.1' to Bun.serve()
and validates /api/reload paths are within cwd() or tmpdir(). Closes C1+C2
from security audit #783.

Co-Authored-By: garagon <garagon@users.noreply.github.com>
Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

* fix: add auth gate to /inspector/events SSE endpoint (C3)

The /inspector/events endpoint had no authentication, unlike /activity/stream
which validates tokens. Now requires the same Bearer header or ?token= query
param check. Closes C3 from security audit #783.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

* fix: sanitize design feedback with trust boundary markers (C4+H5)

Wrap user feedback in <user-feedback> XML markers with tag escaping to
prevent prompt injection via malicious feedback text. Cap accumulated
feedback to last 5 iterations to limit incremental poisoning.
Closes C4 and H5 from security audit #783.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

* fix: harden file/directory permissions to owner-only (C5+H9+M9+M10)

Add mode 0o700 to all mkdirSync calls for state/session directories.
Add mode 0o600 to all writeFileSync calls for session.json, chat.jsonl,
and log files. Add umask 077 to setup script. Prevents auth tokens, chat
history, and browser logs from being world-readable on multi-user systems.
Closes C5, H9, M9, M10 from security audit #783.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

* fix: TOCTOU race in setup symlink creation (C6)

Remove the existence check before mkdir -p (it's idempotent) and validate
the target isn't already a symlink before creating the link. Prevents a
local attacker from racing between the check and mkdir to redirect
SKILL.md writes. Closes C6 from security audit #783.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

* fix: remove CORS wildcard, restrict to localhost (H1)

Replace Access-Control-Allow-Origin: * with http://127.0.0.1 on sidebar
tab/chat endpoints. The Chrome extension uses manifest host_permissions
to bypass CORS entirely, so this only blocks malicious websites from
making cross-origin requests. Closes H1 from security audit #783.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

* fix: make cookie picker auth mandatory (H2)

Remove the conditional if(authToken) guard that skipped auth when
authToken was undefined. Now all cookie picker data/action routes
reject unauthenticated requests. Closes H2 from security audit #783.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

* fix: gate /health token on chrome-extension Origin header

Only return the auth token in /health response when the request Origin
starts with chrome-extension://. The Chrome extension always sends this
origin via manifest host_permissions. Regular HTTP requests (including
tunneled ones from ngrok/SSH) won't get the token. The extension also
has a fallback path through background.js that reads the token from the
state file directly.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

* test: update server-auth test for chrome-extension Origin gating

The test previously checked for 'localhost-only' comment. Now checks for
'chrome-extension://' since the token is gated on Origin header.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

* chore: bump version and changelog (v0.15.7.0)

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

---------

Co-authored-by: Gonzih <gonzih@users.noreply.github.com>
Co-authored-by: Claude Opus 4.6 (1M context) <noreply@anthropic.com>
Co-authored-by: garagon <garagon@users.noreply.github.com>
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