diff --git a/core/src/artifacts/registry.ts b/core/src/artifacts/registry.ts
index 66e2470d1..5dff93cc9 100644
--- a/core/src/artifacts/registry.ts
+++ b/core/src/artifacts/registry.ts
@@ -4,6 +4,7 @@
  * SPDX-License-Identifier: Apache-2.0
  */
 
+import {redactUriPassword} from '../utils/redact_uri.js';
 import {BaseArtifactService} from './base_artifact_service.js';
 import {FileArtifactService} from './file_artifact_service.js';
 import {GcsArtifactService} from './gcs_artifact_service.js';
@@ -29,5 +30,7 @@ export function getArtifactServiceFromUri(uri: string): BaseArtifactService {
     return new FileArtifactService(rootDir);
   }
 
-  throw new Error(`Unsupported artifact service URI: ${uri}`);
+  throw new Error(
+    `Unsupported artifact service URI: ${redactUriPassword(uri)}`,
+  );
 }
diff --git a/core/src/sessions/db/operations.ts b/core/src/sessions/db/operations.ts
index ef5897292..92f7bcb25 100644
--- a/core/src/sessions/db/operations.ts
+++ b/core/src/sessions/db/operations.ts
@@ -5,6 +5,7 @@
  */
 
 import {MikroORM, Options as MikroORMOptions} from '@mikro-orm/core';
+import {redactUriPassword} from '../../utils/redact_uri.js';
 import {
   ENTITIES,
   SCHEMA_VERSION_1_JSON,
@@ -40,7 +41,7 @@ export async function getConnectionOptionsFromUri(
     const {MsSqlDriver} = await import('@mikro-orm/mssql');
     driver = MsSqlDriver;
   } else {
-    throw new Error(`Unsupported database URI: ${uri}`);
+    throw new Error(`Unsupported database URI: ${redactUriPassword(uri)}`);
   }
 
   if (uri.startsWith('sqlite://')) {
diff --git a/core/src/sessions/registry.ts b/core/src/sessions/registry.ts
index c1a077993..6962f7203 100644
--- a/core/src/sessions/registry.ts
+++ b/core/src/sessions/registry.ts
@@ -4,6 +4,7 @@
  * SPDX-License-Identifier: Apache-2.0
  */
 
+import {redactUriPassword} from '../utils/redact_uri.js';
 import {BaseSessionService} from './base_session_service.js';
 import {
   DatabaseSessionService,
@@ -32,5 +33,5 @@ export function getSessionServiceFromUri(uri: string): BaseSessionService {
     return new VertexAiSessionService({});
   }
 
-  throw new Error(`Unsupported session service URI: ${uri}`);
+  throw new Error(`Unsupported session service URI: ${redactUriPassword(uri)}`);
 }
diff --git a/core/src/utils/redact_uri.ts b/core/src/utils/redact_uri.ts
new file mode 100644
index 000000000..b5176a24a
--- /dev/null
+++ b/core/src/utils/redact_uri.ts
@@ -0,0 +1,38 @@
+/**
+ * @license
+ * Copyright 2026 Google LLC
+ * SPDX-License-Identifier: Apache-2.0
+ */
+
+/**
+ * Redacts the password from a connection URI so the URI can be safely included
+ * in error messages and logs.
+ *
+ * A database or session-service connection URI such as
+ * `postgres://user:password@host:5432/db` embeds the password in its userinfo
+ * component. Including such a URI verbatim in a thrown Error or log entry leaks
+ * the credential to wherever those are collected (log files, error-tracking
+ * services, stdout captured by an orchestrator), which is frequently a
+ * different trust boundary from whoever provisioned the connection string.
+ *
+ * This masks the password while keeping the rest of the URI intact for
+ * debugging, mirroring the semantics of Go's `net/url.URL.Redacted()`.
+ *
+ * If the input cannot be parsed as a URL, only its scheme prefix is returned so
+ * that a credential embedded in an otherwise-unparseable string is not leaked.
+ */
+export function redactUriPassword(uri: string): string {
+  try {
+    const url = new URL(uri);
+    if (url.password) {
+      url.password = '***';
+      return url.toString();
+    }
+    return uri;
+  } catch {
+    const schemeEnd = uri.indexOf('://');
+    return schemeEnd === -1
+      ? '<redacted>'
+      : `${uri.slice(0, schemeEnd)}://<redacted>`;
+  }
+}
diff --git a/core/test/utils/redact_uri_test.ts b/core/test/utils/redact_uri_test.ts
new file mode 100644
index 000000000..ec6f1d37a
--- /dev/null
+++ b/core/test/utils/redact_uri_test.ts
@@ -0,0 +1,65 @@
+/**
+ * @license
+ * Copyright 2026 Google LLC
+ * SPDX-License-Identifier: Apache-2.0
+ */
+
+import {describe, expect, it} from 'vitest';
+import {getArtifactServiceFromUri} from '../../src/artifacts/registry.js';
+import {getConnectionOptionsFromUri} from '../../src/sessions/db/operations.js';
+import {getSessionServiceFromUri} from '../../src/sessions/registry.js';
+import {redactUriPassword} from '../../src/utils/redact_uri.js';
+
+describe('redactUriPassword', () => {
+  it('masks the password while keeping the rest of the URI', () => {
+    expect(redactUriPassword('postgres://user:pass@db.host:5432/mydb')).toBe(
+      'postgres://user:***@db.host:5432/mydb',
+    );
+  });
+
+  it('masks the password for unsupported schemes too', () => {
+    expect(redactUriPassword('oracle://admin:hunter2@ora.host/xe')).toBe(
+      'oracle://admin:***@ora.host/xe',
+    );
+  });
+
+  it('leaves a URI without a password unchanged', () => {
+    expect(redactUriPassword('postgres://user@db.host/mydb')).toBe(
+      'postgres://user@db.host/mydb',
+    );
+  });
+
+  it('does not leak anything after the scheme for unparseable input', () => {
+    const out = redactUriPassword('not a url with :hunter2@ inside it');
+    expect(out).not.toContain('hunter2');
+  });
+});
+
+describe('connection-URI errors do not leak the password', () => {
+  it('getConnectionOptionsFromUri redacts the password in its error', async () => {
+    await expect(
+      getConnectionOptionsFromUri('oracle://admin:hunter2@ora.host/xe'),
+    ).rejects.toThrow(/oracle:\/\/admin:\*\*\*@ora\.host\/xe/);
+    await expect(
+      getConnectionOptionsFromUri('oracle://admin:hunter2@ora.host/xe'),
+    ).rejects.not.toThrow(/hunter2/);
+  });
+
+  it('getSessionServiceFromUri redacts the password in its error', () => {
+    expect(() =>
+      getSessionServiceFromUri('oracle://admin:hunter2@ora.host/xe'),
+    ).toThrow(/oracle:\/\/admin:\*\*\*@ora\.host\/xe/);
+    expect(() =>
+      getSessionServiceFromUri('oracle://admin:hunter2@ora.host/xe'),
+    ).not.toThrow(/hunter2/);
+  });
+
+  it('getArtifactServiceFromUri redacts the password in its error', () => {
+    expect(() =>
+      getArtifactServiceFromUri('s3://admin:hunter2@bucket/prefix'),
+    ).toThrow(/s3:\/\/admin:\*\*\*@bucket\/prefix/);
+    expect(() =>
+      getArtifactServiceFromUri('s3://admin:hunter2@bucket/prefix'),
+    ).not.toThrow(/hunter2/);
+  });
+});