fix: harden /api/redux proxy against SSRF (code-scanning #40)#134
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wrigjl wants to merge 1 commit into
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fix: harden /api/redux proxy against SSRF (code-scanning #40)#134wrigjl wants to merge 1 commit into
wrigjl wants to merge 1 commit into
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Resolve the proxy target with the WHATWG URL parser and require it to stay on the configured backend's origin (and an http/https scheme) before calling fetch. Also switch to `redirect: 'manual'` so a misbehaving backend can't 3xx the server toward an internal address; the redirect is forwarded to the client instead. This addresses the js/request-forgery alert at pages/api/redux/[...path].js:34. In practice the previous code was not exploitable for host injection: the user-controlled suffix is appended after "<baseUrl>/", so the WHATWG parser keeps the authority pinned to the backend host. CodeQL flags it anyway because it can't prove that invariant via taint tracking. The explicit origin check makes the guarantee machine-verifiable and closes the additional redirect vector. Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
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What
Hardens the
/api/redux/*proxy handler (pages/api/redux/[...path].js) against server-side request forgery:URLparser and require it to stay on the configured backend's origin, with anhttp:/https:scheme, before callingfetch.redirect: 'manual'so a misbehaving/compromised backend can't3xxthe server toward an internal address. The redirect is forwarded to the client instead.Which scan instance this fixes
Resolves code-scanning alert #40 —
js/request-forgery(SSRF, critical), flagged at thefetch(...)call onpages/api/redux/[...path].js:34("The URL of this request depends on a user-provided value").Note: not actually exploitable (but CodeQL couldn't prove it)
The prior code was not exploitable for host injection. The user-controlled suffix is appended after
"<baseUrl>/", so once the full string is parsed as a URL the authority stays pinned to the backend host — tested payloads (https://evil.com/x,//evil.com/x,@evil.com/x, backslash tricks) all resolved back to the backend origin. CodeQL flags it regardless because taint tracking can't prove that invariant.This change makes the guarantee explicit and machine-verifiable (so the alert clears) and additionally closes the redirect-following vector, which was a real second SSRF path.
Scope / not included
This does not restrict which backend paths or methods a client can reach — the proxy remains a full-surface passthrough to the backend origin. A path allowlist and Cookie/Authorization stripping were discussed as follow-up defense-in-depth but intentionally left out of this focused fix.
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