fix: patch GHSA-6wcg-mqvh-fcvg (#1616)

* fix: patch GHSA-6wcg-mqvh-fcvg PR https://github.com/TecharoHQ/anubis/pull/1015 added the ability for reverse proxies using Anubis in subrequest auth mode to look at the path of a request as there are many rules in the wild that rely on checking the path. This is how access to things like robots.txt or anything in the .well-known directory is unaffected by Anubis. However this logic was also enabled for non-subrequest deployments of Anubis, meaning that a specially crafted request could include a /.well-known/ path in it and then get around Anubis with little effort. This fix gates the logic behind a new plumbed variable named subrequestMode that only fires when Anubis is running in subrequest auth mode. This properly contains that workaround so that the logic does not fire in most deployments. Signed-off-by: Xe Iaso <me@xeiaso.net> * chore: spelling Signed-off-by: Xe Iaso <me@xeiaso.net> --------- Signed-off-by: Xe Iaso <me@xeiaso.net>
2026-05-09 16:42:52 +00:00 · 2026-05-08 19:17:25 -04:00
parent d3a00da448
commit 0491f1fac2
11 changed files with 138 additions and 26 deletions
@@ -272,8 +272,8 @@ func TestPathChecker_XOriginalURI(t *testing.T) {

 	for _, tt := range tests {
 		t.Run(tt.name, func(t *testing.T) {
-			// Create the PathChecker
-			pc, err := NewPathChecker(tt.regex)
+			// Create the PathChecker in subrequest mode so X-Original-URI is honored.
+			pc, err := NewPathChecker(tt.regex, true)
 			if err != nil {
 				if !tt.expectError {
 					t.Fatalf("NewPathChecker() unexpected error: %v", err)
@@ -305,3 +305,108 @@ func TestPathChecker_XOriginalURI(t *testing.T) {
 		})
 	}
 }
+
+// TestPathChecker_GHSA_6wcg_mqvh_fcvg is a regression test for
+// https://github.com/TecharoHQ/anubis/security/advisories/GHSA-6wcg-mqvh-fcvg.
+//
+// PR https://github.com/TecharoHQ/anubis/pull/1015 added the ability for
+// reverse proxies using Anubis in subrequest auth mode to look at the path
+// of a request as there are many rules in the wild that rely on checking
+// the path. This is how access to things like robots.txt or anything in the
+// .well-known directory is unaffected by Anubis.
+//
+// However this logic was also enabled for non-subrequest deployments of Anubis,
+// meaning that a specially crafted request could include a /.well-known/
+// path in it and then get around Anubis with little effort.
+//
+// This fix gates the logic behind a new plumbed variable named subrequestMode
+// that only fires when Anubis is running in subrequest auth mode. This
+// properly contains that workaround so that the logic does not fire in
+// most deployments.
+func TestPathChecker_GHSA_6wcg_mqvh_fcvg(t *testing.T) {
+	tests := []struct {
+		name           string
+		regex          string
+		urlPath        string
+		xOriginalURI   string
+		subRequestMode bool
+		want           bool
+	}{
+		{
+			name:           "default mode ignores spoofed X-Original-URI when real path matches",
+			regex:          "^/admin/.*",
+			urlPath:        "/admin/secret",
+			xOriginalURI:   "/public/index",
+			subRequestMode: false,
+			want:           true,
+		},
+		{
+			name:           "default mode ignores spoofed X-Original-URI when real path does not match",
+			regex:          "^/admin/.*",
+			urlPath:        "/public/index",
+			xOriginalURI:   "/admin/secret",
+			subRequestMode: false,
+			want:           false,
+		},
+		{
+			name:           "default mode without X-Original-URI matches real path",
+			regex:          "^/admin/.*",
+			urlPath:        "/admin/dashboard",
+			xOriginalURI:   "",
+			subRequestMode: false,
+			want:           true,
+		},
+		{
+			name:           "subrequest mode honors X-Original-URI",
+			regex:          "^/admin/.*",
+			urlPath:        "/auth",
+			xOriginalURI:   "/admin/secret",
+			subRequestMode: true,
+			want:           true,
+		},
+		{
+			name:           "subrequest mode falls back to URL.Path when X-Original-URI does not match",
+			regex:          "^/admin/.*",
+			urlPath:        "/admin/dashboard",
+			xOriginalURI:   "/public/index",
+			subRequestMode: true,
+			want:           true,
+		},
+		{
+			name:           "subrequest mode with empty X-Original-URI uses URL.Path",
+			regex:          "^/admin/.*",
+			urlPath:        "/admin/dashboard",
+			xOriginalURI:   "",
+			subRequestMode: true,
+			want:           true,
+		},
+	}
+
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			pc, err := NewPathChecker(tt.regex, tt.subRequestMode)
+			if err != nil {
+				t.Fatalf("NewPathChecker(%q, %v) returned error: %v", tt.regex, tt.subRequestMode, err)
+			}
+
+			req, err := http.NewRequest(http.MethodGet, "http://example.com"+tt.urlPath, nil)
+			if err != nil {
+				t.Fatalf("http.NewRequest: %v", err)
+			}
+
+			if tt.xOriginalURI != "" {
+				req.Header.Set("X-Original-URI", tt.xOriginalURI)
+			}
+
+			got, err := pc.Check(req)
+			if err != nil {
+				t.Fatalf("Check() unexpected error: %v", err)
+			}
+
+			if got != tt.want {
+				t.Errorf("Check() = %v, want %v (subRequestMode=%v, urlPath=%q, X-Original-URI=%q)",
+					got, tt.want, tt.subRequestMode, tt.urlPath, tt.xOriginalURI)
+			}
+		})
+	}
+}