diff --git a/services/projects/issue.go b/services/projects/issue.go
index 3655a000ce..6478ffd2a7 100644
--- a/services/projects/issue.go
+++ b/services/projects/issue.go
@@ -85,7 +85,16 @@ func MoveIssuesOnProjectColumn(ctx context.Context, doer *user_model.User, colum
 				}
 			}
 
-			_, err = db.Exec(ctx, "UPDATE `project_issue` SET project_board_id=?, sorting=? WHERE issue_id=?", column.ID, sorting, issueID)
+			// Scope the update to this issue *in this project*. Without the
+			// project_id predicate, an issue that belongs to several projects
+			// would have every project_issue row rewritten to the target
+			// column, detaching it from all other projects.
+			_, err = db.GetEngine(ctx).Table("project_issue").
+				Where("issue_id = ? AND project_id = ?", issueID, column.ProjectID).
+				Update(map[string]any{
+					"project_board_id": column.ID,
+					"sorting":          sorting,
+				})
 			if err != nil {
 				return err
 			}
diff --git a/tests/integration/api_user_project_test.go b/tests/integration/api_user_project_test.go
index be7ecd99a1..403f922493 100644
--- a/tests/integration/api_user_project_test.go
+++ b/tests/integration/api_user_project_test.go
@@ -37,6 +37,7 @@ func TestAPIUserProjects(t *testing.T) {
 	t.Run("RemoveIssueFromProjectColumn", testAPIUserRemoveIssueFromProjectColumn)
 	t.Run("ListProjectColumnIssues", testAPIUserListProjectColumnIssues)
 	t.Run("MoveProjectIssue", testAPIUserMoveProjectIssue)
+	t.Run("MoveProjectIssueMultiProjectIsolation", testAPIUserMoveProjectIssueMultiProjectIsolation)
 	t.Run("Permissions", testAPIUserProjectPermissions)
 }
 
@@ -502,6 +503,44 @@ func testAPIUserMoveProjectIssue(t *testing.T) {
 	MakeRequest(t, req, http.StatusNotFound)
 }
 
+// Regression for #17: moving an issue's column in one user project must not
+// rewrite its column in other projects the issue also belongs to.
+func testAPIUserMoveProjectIssueMultiProjectIsolation(t *testing.T) {
+	owner := unittest.AssertExistsAndLoadBean(t, &user_model.User{ID: 2})
+	issue := unittest.AssertExistsAndLoadBean(t, &issues_model.Issue{ID: 1})
+
+	p1 := makeUserProject(t, owner)
+	p2 := makeUserProject(t, owner)
+
+	p1ColA := &project_model.Column{Title: "p1-A", ProjectID: p1.ID, CreatorID: owner.ID}
+	assert.NoError(t, project_model.NewColumn(t.Context(), p1ColA))
+	p1ColB := &project_model.Column{Title: "p1-B", ProjectID: p1.ID, CreatorID: owner.ID}
+	assert.NoError(t, project_model.NewColumn(t.Context(), p1ColB))
+	p2Col := &project_model.Column{Title: "p2", ProjectID: p2.ID, CreatorID: owner.ID}
+	assert.NoError(t, project_model.NewColumn(t.Context(), p2Col))
+
+	assert.NoError(t, issues_model.IssueAssignOrRemoveProject(t.Context(), issue, owner, []int64{p1.ID, p2.ID}))
+	assert.NoError(t, projects_service.MoveIssuesOnProjectColumn(t.Context(), owner, p1ColA, map[int64]int64{0: issue.ID}))
+	assert.NoError(t, projects_service.MoveIssuesOnProjectColumn(t.Context(), owner, p2Col, map[int64]int64{0: issue.ID}))
+
+	token := getUserToken(t, owner.Name, auth_model.AccessTokenScopeWriteIssue)
+
+	// move the issue inside p1 only
+	req := NewRequestWithJSON(t, "POST",
+		fmt.Sprintf("/api/v1/users/%s/projects/%d/issues/%d/move", owner.Name, p1.ID, issue.ID),
+		&api.MoveProjectIssueOption{ColumnID: p1ColB.ID},
+	).AddTokenAuth(token)
+	MakeRequest(t, req, http.StatusNoContent)
+
+	// p1 updated as requested
+	pi1 := unittest.AssertExistsAndLoadBean(t, &project_model.ProjectIssue{ProjectID: p1.ID, IssueID: issue.ID})
+	assert.Equal(t, p1ColB.ID, pi1.ProjectColumnID)
+
+	// p2 must be untouched
+	pi2 := unittest.AssertExistsAndLoadBean(t, &project_model.ProjectIssue{ProjectID: p2.ID, IssueID: issue.ID})
+	assert.Equal(t, p2Col.ID, pi2.ProjectColumnID, "issue must remain in its original column in other projects")
+}
+
 func testAPIUserProjectPermissions(t *testing.T) {
 	owner := unittest.AssertExistsAndLoadBean(t, &user_model.User{ID: 2})
 	other := unittest.AssertExistsAndLoadBean(t, &user_model.User{Name: "user5"})