fix: enforce org visibility on organization label read endpoints

The GET /api/v1/orgs/{org}/labels and GET /api/v1/orgs/{org}/labels/{id}
endpoints did not check whether the caller could see the organization, so
labels of a private org were disclosed to non-members (and anonymously for
the list route). Add a reqOrgVisible() middleware mirroring the visibility
check used by org.Get and apply it to the labels group.

routers/api/v1/api.go

@@ -504,6 +504,21 @@ func reqOrgOwnership() func(ctx *context.APIContext) {
 	}
 }
 
+// reqOrgVisible requires the organization to be visible to the doer, or a site admin
+func reqOrgVisible() func(ctx *context.APIContext) {
+	return func(ctx *context.APIContext) {
+		if ctx.Org.Organization == nil {
+			setting.PanicInDevOrTesting("reqOrgVisible: unprepared context")
+			ctx.APIErrorInternal(errors.New("reqOrgVisible: unprepared context"))
+			return
+		}
+		if !organization.HasOrgOrUserVisible(ctx, ctx.Org.Organization.AsUser(), ctx.Doer) {
+			ctx.APIErrorNotFound()
+			return
+		}
+	}
+}
+
 // reqTeamMembership user should be an team member, or a site admin
 func reqTeamMembership() func(ctx *context.APIContext) {
 	return func(ctx *context.APIContext) {
@@ -1673,7 +1688,7 @@ func Routes() *web.Router {
 				m.Combo("/{id}").Get(reqToken(), org.GetLabel).
 					Patch(reqToken(), reqOrgOwnership(), bind(api.EditLabelOption{}), org.EditLabel).
 					Delete(reqToken(), reqOrgOwnership(), org.DeleteLabel)
-			})
+			}, reqOrgVisible())
 			m.Group("/hooks", func() {
 				m.Combo("").Get(org.ListHooks).
 					Post(bind(api.CreateHookOption{}), org.CreateHook)

tests/integration/api_org_test.go

@@ -11,6 +11,7 @@ import (
 	"time"
 
 	auth_model "gitea.dev/models/auth"
+	issues_model "gitea.dev/models/issues"
 	org_model "gitea.dev/models/organization"
 	"gitea.dev/models/perm"
 	repo_model "gitea.dev/models/repo"
@@ -292,3 +293,50 @@ func testAPIDeleteOrgRepos(t *testing.T) {
 		MakeRequest(t, req, http.StatusNoContent) // The org contains no repositories, so the API should return StatusNoContent
 	})
 }
+
+// TestAPIOrgLabelsVisibility ensures the organization label read endpoints honor
+// the organization visibility: labels of a private org must not be disclosed to
+// users who cannot see the org (GHSA: unauthorized access to private org labels).
+func TestAPIOrgLabelsVisibility(t *testing.T) {
+	defer tests.PrepareTestEnv(t)()
+
+	// privated_org (id 23) is a private organization; user5 is its only member.
+	privateOrg := unittest.AssertExistsAndLoadBean(t, &org_model.Organization{ID: 23})
+	label := &issues_model.Label{OrgID: privateOrg.ID, Name: "internal-label", Color: "#aabbcc", Description: "private organization label"}
+	require.NoError(t, issues_model.NewLabel(t.Context(), label))
+
+	listURL := fmt.Sprintf("/api/v1/orgs/%s/labels", privateOrg.Name)
+	getURL := fmt.Sprintf("/api/v1/orgs/%s/labels/%d", privateOrg.Name, label.ID)
+
+	t.Run("NonMemberDenied", func(t *testing.T) {
+		// user2 is not a member of the private org and must not see its labels.
+		token := getUserToken(t, "user2", auth_model.AccessTokenScopeReadOrganization)
+		MakeRequest(t, NewRequest(t, "GET", listURL).AddTokenAuth(token), http.StatusNotFound)
+		MakeRequest(t, NewRequest(t, "GET", getURL).AddTokenAuth(token), http.StatusNotFound)
+	})
+
+	t.Run("AnonymousDenied", func(t *testing.T) {
+		MakeRequest(t, NewRequest(t, "GET", listURL), http.StatusNotFound)
+		MakeRequest(t, NewRequest(t, "GET", getURL), http.StatusNotFound)
+	})
+
+	t.Run("MemberAllowed", func(t *testing.T) {
+		token := getUserToken(t, "user5", auth_model.AccessTokenScopeReadOrganization)
+		resp := MakeRequest(t, NewRequest(t, "GET", listURL).AddTokenAuth(token), http.StatusOK)
+		labels := DecodeJSON(t, resp, &[]*api.Label{})
+		assert.Len(t, *labels, 1)
+		MakeRequest(t, NewRequest(t, "GET", getURL).AddTokenAuth(token), http.StatusOK)
+	})
+
+	t.Run("SiteAdminAllowed", func(t *testing.T) {
+		token := getUserToken(t, "user1", auth_model.AccessTokenScopeReadOrganization)
+		MakeRequest(t, NewRequest(t, "GET", listURL).AddTokenAuth(token), http.StatusOK)
+		MakeRequest(t, NewRequest(t, "GET", getURL).AddTokenAuth(token), http.StatusOK)
+	})
+
+	t.Run("PublicOrgStillReadable", func(t *testing.T) {
+		// org3 (id 3) is a public org with labels; non-members may read them.
+		token := getUserToken(t, "user2", auth_model.AccessTokenScopeReadOrganization)
+		MakeRequest(t, NewRequest(t, "GET", "/api/v1/orgs/org3/labels").AddTokenAuth(token), http.StatusOK)
+	})
+}