Execution: harden cloud callback SSRF and log sanitization (PR #734)

[groupthinking]

Parent governance program

Focused execution unit under #898. PR #734 is the single canonical implementation and remains draft only for the historical provenance boundary and final human review.

Description

Protect the Cloud Task callback sink from SSRF, DNS rebinding, non-public destination bypasses, redirect pivots, unbounded retries, and log forging while preserving legitimate public HTTP(S) callbacks.

Agent login

claude

Agent run ID

session_018e5kEDnS1n4MKvoT6eQ6T4

Declared file scope

• src/youtube_extension/backend/cloud_api_endpoints.py
• tests/unit/test_cloud_routes.py

Focused test paths

• tests/unit/test_cloud_routes.py

Acceptance criteria

• Refresh the existing fix(security): pin cloud callbacks against DNS rebinding #734 branch onto current main.
• Reject malformed and every non-global destination, including CGNAT and IPv6 site-local.
• Resolve once off-loop, reject mixed DNS answers, and pin connections to validated numeric addresses.
• Preserve Host, port, TLS SNI, hostname verification, redirects-disabled behavior, and async I/O.
• Bound dispatch to three public addresses under one deadline and never retry a transmitted POST.
• Sanitize untrusted callback values and exception log values.
• Pass the final focused suite: 122 passed.
• Pass exact-head CI, Coverage, CodeQL, Security, Secret Scan, and Dependency Review.
• Obtain exact-head CodeRabbit approval and resolve all verified findings: 0 unresolved.
• Classify Vercel evidence without treating a Python-only canceled Preview as a runtime failure.
• Resolve the historical pre-dispatch intent/trusted-agent-result boundary.
• Obtain final human review.

Execution receipt

• Declared agent/run: claude / session_018e5kEDnS1n4MKvoT6eQ6T4
• External heartbeat/head: 2026-07-21T09:12:31Z / 4bf4e29c5dca31ca2ae027d9d6db993384c8679b
• Controller login/run: groupthinking / eventrelay-blocker-watch-20260721-0912z
• Canonical branch/PR: claude/determined-maxwell-j5mdyu / fix(security): pin cloud callbacks against DNS rebinding #734
• Claimed timestamp: 2026-07-21T09:12:50Z
• Latest heartbeat: 2026-07-21T09:27:35Z
• Exact head: 115088c13fd518c1245cbecfd7f3e9a8a681d1d0
• Exact-head workflows: CI 29817969888, Coverage 29817969877, CodeQL 29817969870, Security 29817969836, Secret 29817969826, Dependency 29817969916; E2E 29817969857 skipped.
• Review: CodeRabbit exact-head approval at 2026-07-21T09:27:35Z; 0 unresolved threads.

Proven historical contradiction

• PR fix(security): pin cloud callbacks against DNS rebinding #734 was created 2026-07-12T03:42:28Z; issue Execution: harden cloud callback SSRF and log sanitization (PR #734) #911 was created 2026-07-21T08:09:18Z.
• A compliant pre-dispatch snapshot cannot be created retroactively.
• A valid terminal event must be authored by declared login claude; the controller publishes as groupthinking and will not falsify identity.

Deployment evidence

Exact-head Vercel deployment dpl_4KK3dfL3RDqMAeojkhjRDnFpCqFk was canceled by commit-verification policy. The previous verified implementation head produced READY Preview dpl_3gqvTdCTMDY4iHmaASi1RXjWRN78. Vercel builds apps/web, so both are non-authoritative for this Python path. Production is READY on main@2d660c7e5382db1df5c5eba39537aa9d034376bb with no runtime errors in the preceding 24 hours.

Next executable action

Keep #734 draft. Code work is complete. An authorized security owner must choose the explicit legacy-provenance path and provide final review; do not weaken or impersonate the gate.

Safety

No merge, credential mutation, production change, ruleset weakening, fabricated agent identity, or branch deletion was performed.

[linear-code]

MYX-93

[github-actions]

👋 Thanks for opening this issue! It has been automatically labeled for triage.

[coderabbitai]

🔗 Related PRs

#265 - test(e2e): forward Vercel protection-bypass header for preview testing [merged]
#277 - Vercel remediation complete: waitUntil adoption + active middleware + @vercel/functions package (resolves three user-defined outcomes; 16-agent verification-gate consolidated PASS on full matrix) [closed]
#301 - chore: remove dead Railway / stale Vercel references [merged]
#404 - fix(web): sync package-lock with @vercel/functions (unblocks #277 auto-merge) [merged]

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