fix(server): clear server-managed fields in savePlaylist to prevent injection via REST API

Signed-off-by: Deluan <deluan@navidrome.org>

core/playlists/rest_adapter.go

@@ -58,10 +58,16 @@ func (s *playlists) TracksRepository(ctx context.Context, playlistId string, ref
 }
 
 // savePlaylist creates a new playlist, assigning the owner from context.
+// Only Name, Comment, Public, and Rules are user-settable via the REST API.
 func (s *playlists) savePlaylist(ctx context.Context, pls *model.Playlist) (string, error) {
 	usr, _ := request.UserFrom(ctx)
 	pls.OwnerID = usr.ID
-	pls.ID = "" // Force new creation
+	pls.ID = ""               // Force new creation
+	pls.Path = ""             // Server-managed (M3U file path)
+	pls.Sync = false          // Server-managed (M3U sync flag)
+	pls.UploadedImage = ""    // Managed by image upload endpoint
+	pls.ExternalImageURL = "" // Managed by M3U import / plugins only
+	pls.EvaluatedAt = nil     // Server-managed
 	err := s.ds.Playlist(ctx).Put(pls)
 	if err != nil {
 		return "", err

core/playlists/rest_adapter_test.go

@@ -2,10 +2,12 @@ package playlists_test
 
 import (
 	"context"
+	"time"
 
 	"github.com/deluan/rest"
 	"github.com/navidrome/navidrome/core/playlists"
 	"github.com/navidrome/navidrome/model"
+	"github.com/navidrome/navidrome/model/criteria"
 	"github.com/navidrome/navidrome/model/request"
 	"github.com/navidrome/navidrome/tests"
 	. "github.com/onsi/ginkgo/v2"
@@ -56,6 +58,38 @@ var _ = Describe("REST Adapter", func() {
 				Expect(err).ToNot(HaveOccurred())
 				Expect(pls.ID).ToNot(Equal("should-be-cleared"))
 			})
+
+			It("clears server-managed fields to prevent injection via REST API", func() {
+				ctx = request.WithUser(ctx, model.User{ID: "user-1", IsAdmin: false})
+				repo = ps.NewRepository(ctx).(rest.Persistable)
+				now := time.Now()
+				pls := &model.Playlist{
+					Name:             "Legit Playlist",
+					Comment:          "A comment",
+					Public:           true,
+					Rules:            &criteria.Criteria{Expression: criteria.Contains{"title": "test"}},
+					Path:             "/some/path/playlist.m3u",
+					Sync:             true,
+					UploadedImage:    "injected-image-path",
+					ExternalImageURL: "http://evil.example.com/ssrf",
+					EvaluatedAt:      &now,
+				}
+				_, err := repo.Save(pls)
+				Expect(err).ToNot(HaveOccurred())
+
+				saved := mockPlsRepo.Last
+				// User-settable fields are preserved
+				Expect(saved.Name).To(Equal("Legit Playlist"))
+				Expect(saved.Comment).To(Equal("A comment"))
+				Expect(saved.Public).To(BeTrue())
+				Expect(saved.Rules).ToNot(BeNil())
+				// Server-managed fields are cleared
+				Expect(saved.Path).To(BeEmpty())
+				Expect(saved.Sync).To(BeFalse())
+				Expect(saved.UploadedImage).To(BeEmpty())
+				Expect(saved.ExternalImageURL).To(BeEmpty())
+				Expect(saved.EvaluatedAt).To(BeNil())
+			})
 		})
 
 		Describe("Update", func() {