go-chi chi before v5.2.2 Open Redirect via RedirectSlashes

CISA KEV is observed exploitation evidence. FIRST EPSS is a dated prediction of exploitation in the next 30 days. Missing scores are unknown. This collector requests predictions only for explicit CVE aliases in the public NuGet archive; Microsoft release views retain their existing prediction scope.

No collected risk observation for these identifiers. This does not establish absence of exploitation or a zero probability.

chi versions before v5.2.2 contain an open redirect vulnerability in the RedirectSlashes middleware function that uses the Host header to construct redirect URLs. Attackers can manipulate the Host header to redirect users to arbitrary hosts, enabling phishing attacks and credential theft.

Source published

14 Aug 2026 11:35:23 UTC

Source modified

8 Oct 2026 15:21:34 UTC

Observed here

23 Oct 2026 15:48:27 UTC

Source terms

CVE Program Terms of Use

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CVSS 4.0 · 5.1 CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:A/VC:L/VI:L/VA:N/SC:N/SI:N/SA:N

chi versions before v5.2.2 contain an open redirect vulnerability in the RedirectSlashes middleware function that uses the Host header to construct redirect URLs. Attackers can manipulate the Host header to redirect users to arbitrary hosts, enabling phishing attacks and credential theft.

Source published

Aug 14, 2026, 11:35:23 AM (timezone not stated)

Source modified

Oct 8, 2026, 3:21:34 PM (timezone not stated)

Observed here

9 Nov 2026 04:13:27 UTC

Source terms

ENISA EUVD · source terms and attribution apply

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EUVD CVSS 4.0 · 5.1 CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:A/VC:L/VI:L/VA:N/SC:N/SI:N/SA:N

chi versions before v5.2.2 contain an open redirect vulnerability in the RedirectSlashes middleware function that uses the Host header to construct redirect URLs. Attackers can manipulate the Host header to redirect users to arbitrary hosts, enabling phishing attacks and credential theft.

Source published

14 Aug 2026 12:16:43 UTC

Source modified

8 Oct 2026 16:16:53 UTC

Observed here

25 Oct 2026 04:17:18 UTC

Source terms

NIST NVD usage terms; underlying source attribution retained

Original source record · Cite this exact observation · Complete original publisher JSON

This view projects the publisher's source fields for reading; the original JSON retains additional fields and CVE enrichment containers. Attribution: nvd · NIST NVD usage terms; underlying source attribution retained. Source text is retained; field grouping and change labels are provided by ChangeIntel.

CVSS 4.0 · [email protected] · Secondary · 5.1 CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:A/VC:L/VI:L/VA:N/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X

### Summary The RedirectSlashes function in middleware/strip.go is vulnerable to host header injection which leads to open redirect. We consider this a **lower-severity** open redirect, as it can't be exploited from browsers or email clients (requires manipulation of a Host header). ### Details The RedirectSlashes method uses the Host header to construct the redirectURL at this line https://github.com/go-chi/chi/blob/master/middleware/strip.go#L55 The Host header can be manipulated by a user to be any arbitrary host. This leads to open redirect when using the RedirectSlashes middleware ### PoC Create a simple server which uses the RedirectSlashes middleware ``` package main import ( "fmt" "net/http" "github.com/go-chi/chi/v5" "github.com/go-chi/chi/v5/middleware" // Import the middleware package ) func main() { // Create a new Chi router r := chi.NewRouter() // Use the built-in RedirectSlashes middleware r.Use(middleware.RedirectSlashes) // Use middleware.RedirectSlashes // Define a route handler r.Get("/", func(w http.ResponseWriter, r *http.Request) { // A simple response w.Write([]byte("Hello, World!")) }) // Start the server fmt.Println("Starting server on :8080") http.ListenAndServe(":8080", r) } ``` Run the server `go run main.go` Once the server is running, send a request that will trigger the RedirectSlashes function with an arbitrary Host header `curl -iL -H "Host: example.com" http://localhost:8080/test/` Observe that the request will be redirected to example.com ``` curl -L -H "Host: example.com" http://localhost:8080/test/ <!doctype html> <html> <head> <title>Example Domain</title> <meta charset="utf-8" /> <meta http-equiv="Content-type" content="text/html; charset=utf-8" /> <meta name="viewport" content="width=device-width, initial-scale=1" /> <style type="text/css"> body { background-color: #f0f0f2; margin: 0; padding: 0; font-family: -apple-system, system-ui, BlinkMacSystemFont, "Segoe UI", "Open Sans", "Helvetica Neue", Helvetica, Arial, sans-serif; ... snipped ... ``` Without the host header, the response is returned from the test server ``` curl -L http://localhost:8080/test/ 404 page not found ``` ### Impact An open redirect vulnerability allows attackers to trick users into visiting malicious sites. This can lead to phishing attacks, credential theft, and malware distribution, as users trust the application’s domain while being redirected to harmful sites. ### Potential mitigation It seems that the purpose of the RedirectSlashes function is to redirect within the same application. In that case r.RequestURI can be used instead of r.Host by default. If there is a use case to redirect to a different host, a flag can be added to use the Host header instead. As this flag will be controlled by the developer they will make the decision of allowing redirects to arbitrary hosts based on their judgement.

Source published

20 Jun 2025 16:37:47 UTC

Source modified

2 Oct 2026 23:30:06 UTC

Observed here

24 Oct 2026 13:19:41 UTC

Source terms

GitHub Advisory Database · CC-BY-4.0

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CVSS_V4 · CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:A/VC:L/VI:L/VA:N/SC:N/SI:N/SA:N

Publisher rating · MODERATE

## Duplicate Advisory This advisory has been withdrawn because it is a duplicate of GHSA-vrw8-fxc6-2r93. This link is maintained to preserve external references. ## Original Description chi versions before v5.2.2 contain an open redirect vulnerability in the RedirectSlashes middleware function that uses the Host header to construct redirect URLs. Attackers can manipulate the Host header to redirect users to arbitrary hosts, enabling phishing attacks and credential theft.

Source published

14 Aug 2026 12:31:24 UTC

Source modified

2 Oct 2026 23:30:05 UTC

Observed here

24 Oct 2026 13:19:41 UTC

Source terms

GitHub Advisory Database · CC-BY-4.0

Original source record · Cite this exact observation · Complete original publisher JSON

This view projects the publisher's source fields for reading; the original JSON retains additional fields and CVE enrichment containers. Attribution: osv · GitHub Advisory Database · CC-BY-4.0. Source text is retained; field grouping and change labels are provided by ChangeIntel.

CVSS_V4 · CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:A/VC:L/VI:L/VA:N/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X

Publisher rating · MODERATE

Host header injection which leads to open redirect in RedirectSlashes in github.com/go-chi/chi

Source published

21 Jul 2025 15:05:07 UTC

Source modified

15 Aug 2026 05:19:10 UTC

Observed here

24 Oct 2026 13:19:41 UTC

Source terms

OSV · upstream source license applies

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This view projects the publisher's source fields for reading; the original JSON retains additional fields and CVE enrichment containers. Attribution: osv · OSV · upstream source license applies. Source text is retained; field grouping and change labels are provided by ChangeIntel.