fix(security): validate redirect targets in download functions to prevent SSRF bypass#13111
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fix(security): validate redirect targets in download functions to prevent SSRF bypass#13111
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…vent SSRF bypass The existing `validateDownloadUrl` only validates the initial URL, but `fetch()` follows redirects by default. An attacker can provide a safe-looking public URL that redirects to internal endpoints like `http://169.254.169.254/latest/meta-data/`, bypassing SSRF protections. Added `response.redirected` check with `validateDownloadUrl(response.url)` in both `downloadBlob` and `download` functions to validate the final URL after following redirects, before reading the response body. Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>
…load tests MSW was not intercepting fetch() calls, causing 2 tests to fail against the real http://example.com. Switched to globalThis.fetch mocking to match the pattern used in download-blob.test.ts. Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>
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…vent SSRF bypass (#13111) ## Background The existing `validateDownloadUrl` (added in #13085) only validates the initial URL before `fetch()`. Since `fetch()` follows HTTP redirects by default, an attacker can bypass SSRF protections by providing a safe-looking public URL that 302-redirects to internal endpoints (e.g., `http://169.254.169.254/latest/meta-data/`), enabling in-band response body exfiltration through the AI model's response. ## Summary Added `response.redirected` check with `validateDownloadUrl(response.url)` in both `downloadBlob` (`@ai-sdk/provider-utils`) and `download` (`ai`) functions to validate the final URL after following redirects, before reading the response body. ## Manual Verification - `pnpm vitest run packages/provider-utils/src/download-blob.test.ts` — 16 tests pass - `pnpm vitest run packages/provider-utils/src/validate-download-url.test.ts` — 29 tests pass - `pnpm vitest run packages/ai/src/util/download/download.test.ts -t "SSRF"` — 5 tests pass
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✅ Backport PR created: #13127 |
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Background
The existing
validateDownloadUrl(added in #13085) only validates the initial URL beforefetch(). Sincefetch()follows HTTP redirects by default, an attacker can bypass SSRF protections by providing a safe-looking public URL that 302-redirects to internal endpoints (e.g.,http://169.254.169.254/latest/meta-data/), enabling in-band response body exfiltration through the AI model's response.Summary
Added
response.redirectedcheck withvalidateDownloadUrl(response.url)in bothdownloadBlob(@ai-sdk/provider-utils) anddownload(ai) functions to validate the final URL after following redirects, before reading the response body.Manual Verification
pnpm vitest run packages/provider-utils/src/download-blob.test.ts— 16 tests passpnpm vitest run packages/provider-utils/src/validate-download-url.test.ts— 29 tests passpnpm vitest run packages/ai/src/util/download/download.test.ts -t "SSRF"— 5 tests passChecklist
pnpm changesetin the project root)Future Work