diff --git a/weed/s3api/auth_signature_v4.go b/weed/s3api/auth_signature_v4.go
index 8caae3e97..e46cb679a 100644
--- a/weed/s3api/auth_signature_v4.go
+++ b/weed/s3api/auth_signature_v4.go
@@ -354,9 +354,15 @@ func (iam *IdentityAccessManagement) verifyV4Signature(r *http.Request, shouldCh
 	// 8. Verify the signature for each plausible host value: when X-Forwarded-Host carries
 	// no port, the client may have signed the Host header the proxy kept or the forwarded
 	// host and port, and the headers alone cannot tell which.
-	pathForSignature := r.URL.EscapedPath()
+	// A router that rewrote the request path (e.g. the Iceberg catalog's
+	// doubled-/v1 collapse) records the client-sent path in the context;
+	// the signature covers that original path.
+	pathForSignature := s3_constants.GetOriginalRequestPathFromContext(r)
 	if pathForSignature == "" {
-		pathForSignature = r.URL.Path
+		pathForSignature = r.URL.EscapedPath()
+		if pathForSignature == "" {
+			pathForSignature = r.URL.Path
+		}
 	}
 	forwardedPrefix := r.Header.Get("X-Forwarded-Prefix")
 	var matchedHost string
diff --git a/weed/s3api/auth_signature_v4_test.go b/weed/s3api/auth_signature_v4_test.go
index d1601b16e..e2fc67591 100644
--- a/weed/s3api/auth_signature_v4_test.go
+++ b/weed/s3api/auth_signature_v4_test.go
@@ -7,9 +7,12 @@ import (
 	"fmt"
 	"net/http"
 	"slices"
+	"sync"
 	"testing"
 	"time"
 
+	"github.com/seaweedfs/seaweedfs/weed/pb/iam_pb"
+	"github.com/seaweedfs/seaweedfs/weed/s3api/s3_constants"
 	"github.com/seaweedfs/seaweedfs/weed/s3api/s3err"
 )
 
@@ -677,3 +680,42 @@ func TestExtractSignedHeadersCase(t *testing.T) {
 		})
 	}
 }
+
+// A router that internally rewrites the request path (the Iceberg catalog
+// collapses a doubled /v1 prefix) must still verify the signature against
+// the path the client signed, which is kept in the request context.
+func TestVerifyV4SignatureUsesOriginalRequestPath(t *testing.T) {
+	iam := &IdentityAccessManagement{
+		hashes:       make(map[string]*sync.Pool),
+		hashCounters: make(map[string]*int32),
+	}
+	_ = iam.loadS3ApiConfiguration(&iam_pb.S3ApiConfiguration{
+		Identities: []*iam_pb.Identity{
+			{
+				Name: "someone",
+				Credentials: []*iam_pb.Credential{
+					{
+						AccessKey: "access_key_1",
+						SecretKey: "secret_key_1",
+					},
+				},
+				Actions: []string{"Admin", "Read", "Write"},
+			},
+		},
+	})
+
+	req := mustNewSignedRequest(http.MethodGet, "http://127.0.0.1:9000/v1/v1/bucket/namespaces", 0, nil, t)
+
+	// Simulate the rewrite: the routed path is collapsed while the signature
+	// still covers the doubled path the client sent.
+	rewritten := req.Clone(req.Context())
+	rewritten.URL.Path = "/v1/bucket/namespaces"
+	if _, errCode := iam.reqSignatureV4Verify(rewritten); errCode == s3err.ErrNone {
+		t.Fatal("rewritten request verified without the original path; expected a signature mismatch")
+	}
+
+	rewritten = rewritten.WithContext(s3_constants.SetOriginalRequestPathInContext(rewritten.Context(), "/v1/v1/bucket/namespaces"))
+	if _, errCode := iam.reqSignatureV4Verify(rewritten); errCode != s3err.ErrNone {
+		t.Fatalf("signed request rejected after path rewrite: %d", errCode)
+	}
+}
diff --git a/weed/s3api/iceberg/server.go b/weed/s3api/iceberg/server.go
index 5266b8144..8980ebc09 100644
--- a/weed/s3api/iceberg/server.go
+++ b/weed/s3api/iceberg/server.go
@@ -110,6 +110,14 @@ func (s *Server) RegisterRoutes(router *mux.Router) {
 	// audit-logged.
 	router.Use(validateRequestPath)
 
+	// Clients pointed at a catalog URI ending in /v1 still append the API
+	// version themselves, producing /v1/v1/... requests (iceberg-java does
+	// this when configured with a /v1-suffixed URI). Collapse the repeated
+	// segments before routing so those requests reach the intended handler;
+	// a table bucket can never be named "v1" (names require 3-63 chars), so
+	// the rewrite is unambiguous.
+	router.Use(collapseDoubledV1Middleware(router))
+
 	// Configuration endpoint - no auth needed for config
 	router.HandleFunc("/v1/config", s.handleConfig).Methods(http.MethodGet)
 
@@ -181,6 +189,39 @@ func (s *Server) RegisterRoutes(router *mux.Router) {
 	glog.V(2).Infof("Registered Iceberg REST Catalog routes")
 }
 
+// collapseDoubledV1Middleware rewrites /v1/v1/... (and deeper repetitions) to
+// the single-/v1 path and re-dispatches through the router once. The collapsed
+// path never starts with /v1/v1 again, so re-entry cannot recurse. The path
+// the client sent is kept in the request context for SigV4 verification,
+// which must check the signature against what was actually signed.
+func collapseDoubledV1Middleware(router *mux.Router) mux.MiddlewareFunc {
+	return func(next http.Handler) http.Handler {
+		return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+			path := r.URL.Path
+			if path != "/v1/v1" && !strings.HasPrefix(path, "/v1/v1/") {
+				next.ServeHTTP(w, r)
+				return
+			}
+			for path == "/v1/v1" || strings.HasPrefix(path, "/v1/v1/") {
+				path = path[len("/v1"):]
+			}
+			signedPath := r.URL.EscapedPath()
+			if signedPath == "" {
+				signedPath = r.URL.Path
+			}
+			r2 := r.Clone(r.Context())
+			r2.URL.Path = path
+			r2.URL.RawPath = ""
+			r2.RequestURI = r2.URL.EscapedPath()
+			if r.URL.RawQuery != "" {
+				r2.RequestURI += "?" + r.URL.RawQuery
+			}
+			r2 = r2.WithContext(s3_constants.SetOriginalRequestPathInContext(r2.Context(), signedPath))
+			router.ServeHTTP(w, r2)
+		})
+	}
+}
+
 func loggingMiddleware(next http.Handler) http.Handler {
 	return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
 		glog.V(2).Infof("Iceberg REST request: %s %s from %s", r.Method, r.RequestURI, r.RemoteAddr)
diff --git a/weed/s3api/iceberg/server_routes_test.go b/weed/s3api/iceberg/server_routes_test.go
index 67417afda..1d01d702a 100644
--- a/weed/s3api/iceberg/server_routes_test.go
+++ b/weed/s3api/iceberg/server_routes_test.go
@@ -6,6 +6,7 @@ import (
 	"testing"
 
 	"github.com/gorilla/mux"
+	"github.com/seaweedfs/seaweedfs/weed/s3api/s3_constants"
 )
 
 // The catch-all answers anything unrouted, so a path that reaches it is a
@@ -39,3 +40,68 @@ func TestRegisteredRoutesReachAHandler(t *testing.T) {
 		}
 	}
 }
+
+// A catalog URI configured with a trailing /v1 (a common iceberg-java client
+// mistake) produces /v1/v1/... requests; the router collapses the repeated
+// prefix instead of answering "Path not found" or resolving "v1" as a table
+// bucket name.
+func TestDoubledV1PrefixIsCollapsed(t *testing.T) {
+	router := mux.NewRouter().SkipClean(true)
+	(&Server{}).RegisterRoutes(router)
+
+	for _, target := range []string{
+		"/v1/v1/config?warehouse=bucket",
+		// Degenerate repetition collapses in a single pass.
+		"/v1/v1/v1/config",
+	} {
+		rec := httptest.NewRecorder()
+		router.ServeHTTP(rec, httptest.NewRequest(http.MethodGet, target, nil))
+		if rec.Code != http.StatusOK {
+			t.Fatalf("%s: got %d, want 200: %s", target, rec.Code, rec.Body.String())
+		}
+	}
+
+	// /v1/v1/namespaces also matches the {prefix} routes ("v1" can never be a
+	// table bucket name); it must still collapse to the unprefixed endpoint,
+	// which requires auth here rather than answering 404.
+	rec := httptest.NewRecorder()
+	router.ServeHTTP(rec, httptest.NewRequest(http.MethodGet, "/v1/v1/namespaces", nil))
+	if rec.Code != http.StatusUnauthorized {
+		t.Fatalf("/v1/v1/namespaces: got %d, want 401: %s", rec.Code, rec.Body.String())
+	}
+
+	rec = httptest.NewRecorder()
+	router.ServeHTTP(rec, httptest.NewRequest(http.MethodGet, "/v1/nonexistent/path", nil))
+	if rec.Code != http.StatusNotFound {
+		t.Fatalf("/v1/nonexistent/path: got %d, want 404", rec.Code)
+	}
+}
+
+// The rewrite must preserve the client-sent path for SigV4 verification: a
+// signed request is checked against the URI it was signed with, not the
+// collapsed path it was routed under.
+func TestDoubledV1CollapsePreservesOriginalPath(t *testing.T) {
+	router := mux.NewRouter().SkipClean(true)
+	var gotPath, gotSignedPath, gotQuery string
+	router.HandleFunc("/v1/probe", func(w http.ResponseWriter, r *http.Request) {
+		gotPath = r.URL.Path
+		gotQuery = r.URL.RawQuery
+		gotSignedPath = s3_constants.GetOriginalRequestPathFromContext(r)
+	}).Methods(http.MethodGet)
+	router.Use(collapseDoubledV1Middleware(router))
+	router.PathPrefix("/").HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		w.WriteHeader(http.StatusNotFound)
+	})
+
+	rec := httptest.NewRecorder()
+	router.ServeHTTP(rec, httptest.NewRequest(http.MethodGet, "/v1/v1/probe?warehouse=bucket", nil))
+	if gotPath != "/v1/probe" {
+		t.Fatalf("routed path: got %q, want /v1/probe", gotPath)
+	}
+	if gotQuery != "warehouse=bucket" {
+		t.Fatalf("query: got %q, want warehouse=bucket", gotQuery)
+	}
+	if gotSignedPath != "/v1/v1/probe" {
+		t.Fatalf("original signed path: got %q, want /v1/v1/probe", gotSignedPath)
+	}
+}
diff --git a/weed/s3api/s3_constants/header.go b/weed/s3api/s3_constants/header.go
index 5e596b4a1..24a487151 100644
--- a/weed/s3api/s3_constants/header.go
+++ b/weed/s3api/s3_constants/header.go
@@ -331,6 +331,7 @@ const (
 	contextKeyPrincipalArn        contextKey = "s3-principal-arn"
 	contextKeyIdentityClaim       contextKey = "s3-identity-claim"
 	contextKeyIgnoredSessionToken contextKey = "s3-ignored-session-token"
+	contextKeyOriginalRequestPath contextKey = "s3-original-request-path"
 )
 
 // identityHolder is a mutable container for the authenticated identity name,
@@ -453,6 +454,26 @@ func GetIdentityClaimFromContext(r *http.Request) string {
 	return ""
 }
 
+// SetOriginalRequestPathInContext records the path a client actually sent
+// before an internal rewrite (e.g. the Iceberg catalog collapsing a doubled
+// /v1 prefix). SigV4 verification must run against this path: the client
+// signed the URI it requested, not the normalized path it was routed with.
+func SetOriginalRequestPathInContext(ctx context.Context, path string) context.Context {
+	if path == "" {
+		return ctx
+	}
+	return context.WithValue(ctx, contextKeyOriginalRequestPath, path)
+}
+
+// GetOriginalRequestPathFromContext returns the pre-rewrite request path
+// recorded by SetOriginalRequestPathInContext, or "" when unset.
+func GetOriginalRequestPathFromContext(r *http.Request) string {
+	if path, ok := r.Context().Value(contextKeyOriginalRequestPath).(string); ok {
+		return path
+	}
+	return ""
+}
+
 // IgnoreSessionTokenInContext marks the request's session token as tolerated
 // rather than authenticated: a statically configured access key signed the
 // request, so the token (which credential vendors like Unity Catalog emit on