[frontegg-david]

Summary

SSRF hardening: pinned transport never reuses pooled sockets

Since 2.5.1, safeFetch pins every Node connection to the address assertUrlSafe validated, through a custom lookup. That closes the DNS-rebinding window between the check and the connect. There was one remaining gap: Node ≥ 19's http.globalAgent keeps sockets alive and pools them by host:port, ignoring lookup. A pinned request could reuse a keep-alive socket that another client in the process had already connected to a different (internal) address.

nodePinnedTransport now passes agent: false, so every request and every redirect hop opens a fresh socket through the pinned lookup.

Regression tests

• Pooled socket (ssrf.spec.ts). First, warm http.globalAgent with a socket to 127.0.0.1. Then a request to the same host:port pinned to a public address must not reach the loopback server. This test failed before the fix.
• DNS rebinding (ssrf.spec.ts, generator.spec.ts). Validation answers a public address and a connect-time dns.lookup would answer loopback. safeFetch, fromURL and external $ref resolution must never reach the loopback server, and must never call the connect-time lookup. I checked that all three fail when the pinned lookup is removed.

Docs

docs/ssrf-prevention.md "How It Works" now covers DNS validation, connection pinning, fresh sockets and per-hop redirect checks, plus the limits of fetchImpl and edge runtimes.

Dependency updates (supersedes #34, #35, #36)

• chore(deps): bump yaml from 2.9.0 to 2.9.1 #36: yaml 2.9.0 → 2.9.1
• chore(deps): bump @apidevtools/json-schema-ref-parser from 15.5.1 to 16.0.2 #35: @apidevtools/json-schema-ref-parser 15.5.1 → 16.0.3 (range ^16.0.2)
• chore(deps-dev): bump the dev-dependencies group across 1 directory with 6 updates #34: jest 30, @swc/core 1.16, esbuild 0.28, @types/node 26, @types/jest 30, zod 4.6
  • Fixes the failing typecheck from chore(deps-dev): bump the dev-dependencies group across 1 directory with 6 updates #34: @types/node 26 no longer accepts a Uint8Array<ArrayBufferLike> as a BlobPart, so multipart binary parts are copied into an ArrayBuffer-backed view first. The e2e wire test still asserts the bytes arrive verbatim.
  • Jest 30 renamed --testPathPattern to --testPathPatterns (test:integration script).

⚠️ Breaking change

json-schema-ref-parser 16 requires Node.js ≥ 22.19.0 (Node 20 reached end-of-life in April 2026). engines.node is now >=22.19.0, and the CI matrix drops 20.x.

Verification

• yarn build
• tsc --noEmit
• yarn test:coverage: 1050 tests, 100% statements/branches/functions/lines
• yarn test:unit and yarn test:integration
• yarn test:e2e: 56 tests
• All run locally on Node 24.

Summary by CodeRabbit

• Security

  • Node.js requests now connect to the address validated during URL checks and use a fresh connection for each request. Redirects are revalidated, and redirects are not followed for external reference fetches.
  • On Web or edge runtimes, or when using a custom fetch implementation, connection pinning is unavailable; use host allowlists and network egress controls with untrusted input.

• Bug Fixes

  • Multipart requests now preserve byte data when serializing Uint8Array values.

• Compatibility

  • The minimum supported Node.js version is now 22.19.0.

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📥 Commits

Reviewing files that changed from the base of the PR and between 525862a and 1946fe9.

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• yarn.lock is excluded by !**/yarn.lock, !**/*.lock

📒 Files selected for processing (8)

• .github/workflows/push.yml
• CLAUDE.md
• docs/ssrf-prevention.md
• package.json
• src/__tests__/generator.spec.ts
• src/__tests__/ssrf.spec.ts
• src/request-builder.ts
• src/ssrf.ts

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Walkthrough

Node requests now use fresh sockets to preserve pinned-address behavior. The changes add DNS-rebinding and socket-pooling tests, update Node and test-tool versions, document SSRF safeguards, and copy multipart byte arrays before creating a Blob.

Changes

Pinned request transport

Layer / File(s)	Summary
Node runtime baseline .github/workflows/push.yml, package.json	The CI matrix tests Node 22.x and 24.x. The minimum supported Node.js version is 22.19.0.
Socket isolation and regression coverage src/ssrf.ts, src/__tests__/ssrf.spec.ts, src/__tests__/generator.spec.ts, docs/ssrf-prevention.md	nodePinnedTransport disables agent pooling. Tests cover DNS rebinding and pooled socket reuse. Documentation describes request pinning, redirects, and runtime limitations.

Test and parser toolchain

Layer / File(s)	Summary
Test and parser versions package.json, CLAUDE.md	The integration-test script uses Jest’s --testPathPatterns option. Dependency ranges and documented Jest and JSON Schema reference parser versions are updated.

Multipart byte serialization

Layer / File(s)	Summary
Copy multipart byte arrays src/request-builder.ts	Multipart serialization copies Uint8Array values before passing them to Blob.

Priority: ➖ Normal

Estimated code review effort: 3 (Moderate) | ~20 minutes

Change: Bug fix

Merge Risk: ⚪ Minimal · up to 1946f

No merge-blocking issue is established; the change is ready for normal checks.

🚥 Pre-merge checks | ✅ 5

✅ Passed checks (5 passed)

Check name	Status	Explanation
Description Check	✅ Passed	Check skipped - CodeRabbit’s high-level summary is enabled.
Title check	✅ Passed	The title clearly summarizes the primary SSRF connection-isolation fix and also identifies the dependency updates.
Docstring Coverage	✅ Passed	Docstring coverage is 100.00% which is sufficient. The required threshold is 80.00%. Docstring coverage is scoped to functions touched by this diff. Analyzed 2 functions across 4 files. (4 skipped: 4 …
Linked Issues check	✅ Passed	Check skipped because no linked issues were found for this pull request.
Out of Scope Changes check	✅ Passed	Check skipped because no linked issues were found for this pull request.

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_{A rabbit checks the pinned address with care.
A fresh socket carries each request through air.
No pooled path can change the route.
Byte copies keep multipart values stout.
New test versions hop along the way.
The rabbit thumps, then bounds away.}

_{Comment @coderabbitai help to get the list of available commands.}