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CORS Reflect Origin #1385

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Merged
Mzack9999 merged 12 commits into from
Jul 2, 2026
Merged

CORS Reflect Origin #1385

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6b47e44
added eviction strategy
orr-a-security Nov 5, 2025
2f2071b
added tests for eviction strategy
orr-a-security Nov 10, 2025
f9a1dd1
Merge pull request #1275 from orrk-litt/feature/eviction-strategy
Mzack9999 Nov 24, 2025
e1332ce
Revert "feat(server) added eviction strategy"
Mzack9999 Nov 24, 2025
0eb8a06
Merge pull request #1286 from projectdiscovery/revert-1275-feature/ev…
Mzack9999 Nov 24, 2025
4da329c
Merge pull request #1317 from projectdiscovery/dev
dogancanbakir Jan 27, 2026
b9eba1d
chore(deps): bump github.com/refraction-networking/utls
dependabot[bot] Feb 19, 2026
307efeb
Merge pull request #1334 from projectdiscovery/dependabot/go_modules/…
dogancanbakir Feb 24, 2026
810180a
Merge pull request #1343 from projectdiscovery/dev
dogancanbakir Mar 10, 2026
148d9f7
reflect origin
rsrdesarrollo Jun 4, 2026
e0c7883
harden cors
Mzack9999 Jul 2, 2026
00248bc
Merge remote-tracking branch 'origin/dev' into rsrdesarrollo/main
Mzack9999 Jul 2, 2026
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17 changes: 15 additions & 2 deletions pkg/server/http_server.go
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Original file line number Diff line number Diff line change
Expand Up @@ -490,15 +490,28 @@ func (h *HTTPServer) pollHandler(w http.ResponseWriter, req *http.Request) {

func (h *HTTPServer) corsMiddleware(next http.Handler) http.Handler {
return http.HandlerFunc(func(w http.ResponseWriter, req *http.Request) {
allowOrigin := h.options.OriginURL
// When the allowed origin is the wildcard, reflect the request's Origin
// instead of returning "*". Browsers reject responses that combine
// "Access-Control-Allow-Origin: *" with "Access-Control-Allow-Credentials: true",
// so reflecting the origin keeps the default permissive while remaining valid.
if h.options.OriginURL == "*" {
if origin := req.Header.Get("Origin"); origin != "" {
allowOrigin = origin
}
// Response varies by Origin, so caches must key on it.
w.Header().Add("Vary", "Origin")
}

// Set CORS headers for the preflight request
if req.Method == http.MethodOptions {
w.Header().Set("Access-Control-Allow-Origin", h.options.OriginURL)
w.Header().Set("Access-Control-Allow-Origin", allowOrigin)
w.Header().Set("Access-Control-Allow-Credentials", "true")
w.Header().Set("Access-Control-Allow-Headers", "Content-Type, Authorization")
w.WriteHeader(http.StatusNoContent)
return
}
w.Header().Set("Access-Control-Allow-Origin", h.options.OriginURL)
w.Header().Set("Access-Control-Allow-Origin", allowOrigin)
w.Header().Set("Access-Control-Allow-Credentials", "true")
Comment on lines +498 to 515

@coderabbitai coderabbitai Bot Jun 4, 2026

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⚠️ Potential issue | 🟠 Major | ⚡ Quick win

Add Vary: Origin when Access-Control-Allow-Origin is dynamic.

When OriginURL == "*", Access-Control-Allow-Origin varies per request origin, but the response currently does not advertise that variance. Shared caches/CDNs can serve a response with the wrong CORS origin to another client.

Suggested patch 
 		if h.options.OriginURL == "*" {
 			acao_url = req.Header.Get("Origin")
+			w.Header().Add("Vary", "Origin")
 		} else {
 			acao_url = h.options.OriginURL
 		}
📝 Committable suggestion

‼️ IMPORTANT
Carefully review the code before committing. Ensure that it accurately replaces the highlighted code, contains no missing lines, and has no issues with indentation. Thoroughly test & benchmark the code to ensure it meets the requirements.

Suggested change
if h.options.OriginURL == "*" {
acao_url = req.Header.Get("Origin")
} else {
acao_url = h.options.OriginURL
}
// Set CORS headers for the preflight request
if req.Method == http.MethodOptions {
w.Header().Set("Access-Control-Allow-Origin", h.options.OriginURL)
w.Header().Set("Access-Control-Allow-Origin", acao_url)
w.Header().Set("Access-Control-Allow-Credentials", "true")
w.Header().Set("Access-Control-Allow-Headers", "Content-Type, Authorization")
w.WriteHeader(http.StatusNoContent)
return
}
w.Header().Set("Access-Control-Allow-Origin", h.options.OriginURL)
w.Header().Set("Access-Control-Allow-Origin", acao_url)
w.Header().Set("Access-Control-Allow-Credentials", "true")
if h.options.OriginURL == "*" {
acao_url = req.Header.Get("Origin")
w.Header().Add("Vary", "Origin")
} else {
acao_url = h.options.OriginURL
}
// Set CORS headers for the preflight request
if req.Method == http.MethodOptions {
w.Header().Set("Access-Control-Allow-Origin", acao_url)
w.Header().Set("Access-Control-Allow-Credentials", "true")
w.Header().Set("Access-Control-Allow-Headers", "Content-Type, Authorization")
w.WriteHeader(http.StatusNoContent)
return
}
w.Header().Set("Access-Control-Allow-Origin", acao_url)
w.Header().Set("Access-Control-Allow-Credentials", "true")
🤖 Prompt for AI Agents 
Verify each finding against current code. Fix only still-valid issues, skip the
rest with a brief reason, keep changes minimal, and validate.

In `@pkg/server/http_server.go` around lines 492 - 507, The CORS handling sets
Access-Control-Allow-Origin dynamically when h.options.OriginURL == "*"
(computed into acao_url from req.Header.Get("Origin")) but does not set the Vary
header; add w.Header().Add("Vary", "Origin") whenever
Access-Control-Allow-Origin is determined from the request (i.e., in the branch
where h.options.OriginURL == "*") so both the preflight (req.Method ==
http.MethodOptions) and normal response paths include Vary: Origin to prevent
incorrect cached responses.

w.Header().Set("Access-Control-Allow-Headers", "Content-Type, Authorization")
next.ServeHTTP(w, req)
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