diff --git a/e2e/common/oauth2-fixtures.mjs b/e2e/common/oauth2-fixtures.mjs
index 7faa38e9cf..c9eec6c100 100644
--- a/e2e/common/oauth2-fixtures.mjs
+++ b/e2e/common/oauth2-fixtures.mjs
@@ -211,6 +211,75 @@ export async function ensureOidcClient(adminToken, request, clientId) {
   });
 }
 
+/**
+ * Give each worker/run its own provider. No root-realm provider GET/PUT is performed,
+ * so this setup cannot overwrite settings being changed by the other OAuth/UMA specs.
+ */
+export async function createDevicePkceRealm(adminToken, request, realm, clientId, owner) {
+  const realmUrl = `${OPENAM_BASE}/json/realms/root/realms/${realm}`;
+  const oauthUrl = `${OPENAM_BASE}/oauth2/realms/root/realms/${realm}`;
+  const headers = adminHeaders(adminToken, CONFIG_VERSION);
+  async function requireSuccess(response, operation) {
+    if (!response.ok()) throw new Error(`${operation}: ${response.status()} ${await response.text()}`);
+  }
+  await requireSuccess(await request.post(`${OPENAM_BASE}/json/global-config/realms?_action=create`, {
+    headers, data: { name: realm, parentPath: "/", active: true, aliases: [] },
+  }), "create PKCE realm");
+  await requireSuccess(await request.post(`${realmUrl}/realm-config/services/oauth-oidc?_action=create`, {
+    headers,
+    data: {
+      advancedOAuth2Config: { clientsCanSkipConsent: true, supportedScopes: [SCOPE], defaultScopes: [SCOPE] },
+      advancedOIDCConfig: { allowDynamicRegistration: true },
+    },
+  }), "create PKCE provider");
+  // A new realm has no AgentService container. Dynamic registration creates it through
+  // the product's supported registration path before the admin API writes our client.
+  await requireSuccess(await request.post(`${oauthUrl}/connect/register`, {
+    data: { redirect_uris: [REDIRECT_URI], client_name: "PKCE realm bootstrap" },
+  }), "bootstrap PKCE AgentService");
+  await requireSuccess(await request.put(`${realmUrl}/realm-config/agents/OAuth2Client/${clientId}`, {
+    headers: adminHeaders(adminToken, AGENT_VERSION),
+    data: {
+      "com.forgerock.openam.oauth2provider.clientType": "Public",
+      "com.forgerock.openam.oauth2provider.scopes": [`[0]=${SCOPE}`],
+      "com.forgerock.openam.oauth2provider.defaultScopes": [`[0]=${SCOPE}`],
+      "com.forgerock.openam.oauth2provider.grantTypes": ["[0]=urn:ietf:params:oauth:grant-type:device_code"],
+      "com.forgerock.openam.oauth2provider.responseTypes": ["[0]=device_code"],
+      "com.forgerock.openam.oauth2provider.tokenEndPointAuthMethod": "none",
+      isConsentImplied: true,
+      sunIdentityServerDeviceStatus: "Active",
+    },
+  }), "create PKCE client");
+  // A fresh realm must provision its resource owner rather than rely on a root demo account.
+  await requireSuccess(await request.post(`${realmUrl}/users?_action=create`, {
+    headers: adminHeaders(adminToken, { "Accept-API-Version": "resource=3.0,protocol=2.1" }),
+    data: {
+      username: owner.username, userpassword: owner.password,
+      sn: "PKCE", cn: "PKCE Test User", givenName: "PKCE",
+    },
+  }), "create PKCE resource owner");
+  return { realmUrl, oauthUrl };
+}
+
+export async function deleteDevicePkceRealm(adminToken, request, realm, username) {
+  // Realm deletion does not remove entries from its shared LDAP identity store.
+  if (username) {
+    const user = await request.delete(`${OPENAM_BASE}/json/realms/root/realms/${realm}/users/${encodeURIComponent(username)}`, {
+      headers: adminHeaders(adminToken, { "Accept-API-Version": "resource=3.0,protocol=2.1" }),
+    });
+    if (!user.ok() && user.status() !== 404) {
+      throw new Error(`delete PKCE resource owner: ${user.status()} ${await user.text()}`);
+    }
+  }
+  const id = Buffer.from(`/${realm}`).toString("base64url");
+  const response = await request.delete(`${OPENAM_BASE}/json/global-config/realms/${id}`, {
+    headers: adminHeaders(adminToken, CONFIG_VERSION),
+  });
+  if (!response.ok() && response.status() !== 404) {
+    throw new Error(`delete PKCE realm: ${response.status()} ${await response.text()}`);
+  }
+}
+
 export async function ensureResourceServerClient(adminToken, request, clientId) {
   await ensureClient(adminToken, request, clientId, {
     "userpassword": RS_CLIENT_SECRET,
@@ -429,3 +498,4 @@ export async function protectionApiToken(request, clientId, username, password)
 export async function authorizationApiToken(request, clientId, username, password) {
   return resourceServerToken(request, clientId, username, password, "uma_authorization");
 }
+
diff --git a/e2e/oauth2/device-pkce-test.spec.mjs b/e2e/oauth2/device-pkce-test.spec.mjs
new file mode 100644
index 0000000000..413447c86d
--- /dev/null
+++ b/e2e/oauth2/device-pkce-test.spec.mjs
@@ -0,0 +1,167 @@
+/*
+ * The contents of this file are subject to the terms of the Common Development and
+ * Distribution License (the License). You may not use this file except in compliance with the
+ * License.
+ *
+ * You can obtain a copy of the License at legal/CDDLv1.0.txt. See the License for the
+ * specific language governing permission and limitations under the License.
+ *
+ * When distributing Covered Software, include this CDDL Header Notice in each file and include
+ * the License file at legal/CDDLv1.0.txt. If applicable, add the following below the CDDL
+ * Header, with the fields enclosed by brackets [] replaced by your own identifying
+ * information: "Portions copyright [year] [name of copyright owner]".
+ *
+ * Copyright 2026 Aravind Yedmala.
+ */
+
+import { randomUUID } from "node:crypto";
+import { test, expect } from "@playwright/test";
+import { getAdminToken, PASSWORD } from "../common/openam-commons.mjs";
+import { SCOPE, createDevicePkceRealm, deleteDevicePkceRealm } from "../common/oauth2-fixtures.mjs";
+
+// HTTP coverage for GHSA-h93p-35jm-rj83, part of #1223. Unlike the Java resource tests, these
+// assertions survive removal of Restlet and exercise challenge persistence through the token store.
+const CLIENT_ID = "test_device_pkce_app";
+const USERNAME = `pkce${randomUUID().replaceAll("-", "")}`;
+const DEVICE_GRANT = "urn:ietf:params:oauth:grant-type:device_code";
+let ENDPOINT;
+// RFC 7636 Appendix B's S256 test vector; plain uses the same valid 43-character verifier.
+const VERIFIER = "dBjftJeZ4CVP-mB92K27uhbUJU1p1r_wW1gFWFOEjXk";
+const WRONG_VERIFIER = "a".repeat(43);
+const METHODS = [
+  { name: "S256", challenge: "E9Melhoa2OwvFrEMTJguCHaoeK1t8URWbuGJSstw-cM", method: "S256" },
+  { name: "plain", challenge: VERIFIER, method: "plain" },
+  { name: "omitted (defaults to plain)", challenge: VERIFIER },
+];
+
+async function issueCode(request, { challenge, method } = {}) {
+  const form = { client_id: CLIENT_ID, response_type: "device_code", scope: SCOPE };
+  if (challenge !== undefined) form.code_challenge = challenge;
+  if (method !== undefined) form.code_challenge_method = method;
+  return request.post(`${ENDPOINT}/device/code`, { form, headers: { Accept: "application/json" } });
+}
+
+async function newCode(request, parameters) {
+  const response = await issueCode(request, parameters);
+  expect(response.status(), `device code issuance: ${await response.text()}`).toBe(200);
+  const body = await response.json();
+  expect(body.device_code).toEqual(expect.any(String));
+  expect(body.device_code.length).toBeGreaterThan(0);
+  expect(body.user_code).toEqual(expect.any(String));
+  expect(body.user_code.length).toBeGreaterThan(0);
+  return body;
+}
+
+async function approveCode(request, userCode, sessionToken) {
+  // This is the documented non-browser submission, including the session-bound CSRF value.
+  const response = await request.post(`${ENDPOINT}/device/user`, {
+    form: { user_code: userCode, csrf: sessionToken },
+    // Each test has a different request context: carry the owner session explicitly.
+    headers: { Cookie: `iPlanetDirectoryPro=${sessionToken}` },
+    maxRedirects: 0,
+  });
+  expect(response.status(), `device approval: ${await response.text()}`).toBe(200);
+}
+
+function redeem(request, deviceCode, verifier) {
+  const form = { grant_type: DEVICE_GRANT, client_id: CLIENT_ID, device_code: deviceCode };
+  if (verifier !== undefined) form.code_verifier = verifier;
+  return request.post(`${ENDPOINT}/access_token`, { form, headers: { Accept: "application/json" } });
+}
+
+async function expectOAuthError(response, error) {
+  expect(response.status(), `expected ${error}: ${await response.text()}`).toBe(400);
+  const body = await response.json();
+  expect(body.error).toBe(error);
+  expect(body).not.toHaveProperty("access_token");
+  expect(body).not.toHaveProperty("refresh_token");
+  expect(body).not.toHaveProperty("id_token");
+}
+
+async function expectTokensForUser(request, deviceCode, verifier) {
+  const response = await redeem(request, deviceCode, verifier);
+  expect(response.status(), `token redemption: ${await response.text()}`).toBe(200);
+  const body = await response.json();
+  expect(body.access_token).toEqual(expect.any(String));
+  expect(body.access_token.length).toBeGreaterThan(0);
+  const userInfo = await request.get(`${ENDPOINT}/userinfo`, {
+    headers: { Authorization: `Bearer ${body.access_token}`, Accept: "application/json" },
+  });
+  expect(userInfo.status(), `userinfo: ${await userInfo.text()}`).toBe(200);
+  expect((await userInfo.json()).sub).toBe(USERNAME);
+}
+
+test.describe("Device authorization PKCE over HTTP", () => {
+  let sessionToken;
+  let adminToken;
+  let realm;
+
+  test.beforeAll(async ({ request }) => {
+    adminToken = await getAdminToken(request);
+    expect(adminToken, "administrator authentication is required; security coverage must not silently skip").toBeTruthy();
+    realm = `devicepkce${randomUUID().replaceAll("-", "")}`;
+    const fixture = await createDevicePkceRealm(adminToken, request, realm, CLIENT_ID, { username: USERNAME, password: PASSWORD });
+    ENDPOINT = fixture.oauthUrl;
+    // Authenticate in the isolated realm; a root-realm session is not sufficient here.
+    const authentication = await request.post(`${fixture.realmUrl}/authenticate`, {
+      headers: {
+        "X-OpenAM-Username": USERNAME, "X-OpenAM-Password": PASSWORD,
+        "Content-Type": "application/json", "Accept-API-Version": "resource=2.0,protocol=1.0",
+      },
+    });
+    expect(authentication.status(), "resource-owner authentication").toBe(200);
+    sessionToken = (await authentication.json()).tokenId;
+    expect(sessionToken, "resource-owner authentication is required").toBeTruthy();
+  });
+
+  test.afterAll(async ({ request }) => {
+    if (adminToken && realm) await deleteDevicePkceRealm(adminToken, request, realm, USERNAME);
+  });
+
+  for (const method of ["bogus", "s256", "PLAIN", ""]) {
+    test(`issuance rejects challenge method ${JSON.stringify(method)}`, async ({ request }) => {
+      await expectOAuthError(await issueCode(request, { ...METHODS[0], method }), "invalid_request");
+    });
+  }
+
+  for (const parameters of METHODS) {
+    test(`${parameters.name}: correct verifier completes the device flow`, async ({ request }) => {
+      const code = await newCode(request, parameters);
+      await approveCode(request, code.user_code, sessionToken);
+      await expectTokensForUser(request, code.device_code, VERIFIER);
+    });
+
+    for (const attempt of [
+      { name: "missing", verifier: undefined, error: "invalid_request" },
+      { name: "wrong", verifier: WRONG_VERIFIER, error: "invalid_grant" },
+    ]) {
+      test(`${parameters.name}: ${attempt.name} verifier cannot redeem or consume an approved code`,
+        async ({ request }) => {
+          const code = await newCode(request, parameters);
+          await approveCode(request, code.user_code, sessionToken);
+          await expectOAuthError(await redeem(request, code.device_code, attempt.verifier), attempt.error);
+          // A rejection alone could pass if the flow were broken for everyone. Redeeming the SAME code
+          // with the right verifier proves both that approval worked and that the attack did not consume it.
+          await expectTokensForUser(request, code.device_code, VERIFIER);
+        });
+    }
+  }
+
+  for (const attempt of [
+    { name: "missing", verifier: undefined, error: "invalid_request" },
+    { name: "wrong", verifier: WRONG_VERIFIER, error: "invalid_grant" },
+  ]) {
+    test(`S256: ${attempt.name} verifier is rejected before user approval`, async ({ request }) => {
+      const code = await newCode(request, METHODS[0]);
+      await expectOAuthError(await redeem(request, code.device_code, attempt.verifier), attempt.error);
+      await approveCode(request, code.user_code, sessionToken);
+      await expectTokensForUser(request, code.device_code, VERIFIER);
+    });
+  }
+
+  test("a device flow without a challenge still works without a verifier", async ({ request }) => {
+    const code = await newCode(request);
+    await approveCode(request, code.user_code, sessionToken);
+    await expectTokensForUser(request, code.device_code);
+  });
+});