diff --git a/.changeset/trusted-oauth-token-regions.md b/.changeset/trusted-oauth-token-regions.md
new file mode 100644
index 0000000000..9f3abec23a
--- /dev/null
+++ b/.changeset/trusted-oauth-token-regions.md
@@ -0,0 +1,5 @@
+---
+"@executor-js/sdk": patch
+---
+
+Restrict callback-selected OAuth token endpoints to supported Datadog regions and validate persisted regional endpoints before refreshing credentials.
diff --git a/packages/core/sdk/src/executor.ts b/packages/core/sdk/src/executor.ts
index 0f338405cd..2a6b823a5f 100644
--- a/packages/core/sdk/src/executor.ts
+++ b/packages/core/sdk/src/executor.ts
@@ -212,6 +212,7 @@ import {
   isUnusableSuccessTokenResponse,
   optionalScopesFromAuthorizationUrl,
   shouldRefreshToken,
+  tokenEndpointForRefresh,
   type OAuth2TokenResponse,
   type OAuthEndpointUrlPolicy,
 } from "./oauth-helpers";
@@ -2694,7 +2695,13 @@ export const createExecutor = <const TPlugins extends readonly AnyPlugin[] = rea
         // Refresh against the region the code was redeemed at when one was
         // recorded at connect time (multi-site providers like Datadog), else
         // the oauth_client's configured token endpoint.
-        const tokenUrl = row.oauth_token_url ? String(row.oauth_token_url) : clientRow.tokenUrl;
+        const tokenUrl = tokenEndpointForRefresh(
+          clientRow.tokenUrl,
+          row.oauth_token_url == null ? null : String(row.oauth_token_url),
+        );
+        if (tokenUrl === undefined) {
+          return yield* reauth("Stored OAuth token endpoint is no longer trusted; reconnect.");
+        }
 
         // Enterprise-managed authorization (the ID-JAG grant profile) issues NO
         // refresh token by design — the identity assertion in `refresh_item_id`
diff --git a/packages/core/sdk/src/oauth-helpers.ts b/packages/core/sdk/src/oauth-helpers.ts
index b8b11714c2..178beaa277 100644
--- a/packages/core/sdk/src/oauth-helpers.ts
+++ b/packages/core/sdk/src/oauth-helpers.ts
@@ -307,17 +307,20 @@ export const optionalScopesFromAuthorizationUrl = (authorizationUrl: string): re
 // statically advertises `app.datadoghq.com`. Redeeming the code at the
 // advertised host then fails with `invalid_grant`.
 //
-// `rebindTokenEndpointHostToCallbackDomain` swaps ONLY the hostname of the
-// configured token URL to the callback-supplied host, and ONLY when that host
-// is a sibling subdomain of the configured one (same parent after stripping the
-// leftmost DNS label, e.g. `app.datadoghq.com` and `us5.datadoghq.com` both
-// reduce to `datadoghq.com`). The token request carries the client secret, the
-// code, and the PKCE verifier, so an attacker-influenced `domain` must never be
-// able to point it at an arbitrary origin. Anything that fails the sibling
-// check, fails to parse, or isn't https falls back to the configured URL
-// unchanged.
+// Token requests carry client credentials and grants. Callback data can select
+// only an explicitly supported Datadog region, never a generic DNS sibling.
+// Keep this list limited to the commercial datadoghq.com region family that
+// this integration supports; other providers use their configured endpoint.
 // ---------------------------------------------------------------------------
 
+const DATADOG_REGIONAL_TOKEN_HOSTS: ReadonlySet<string> = new Set([
+  "app.datadoghq.com",
+  "us3.datadoghq.com",
+  "us5.datadoghq.com",
+  "ap1.datadoghq.com",
+  "ap2.datadoghq.com",
+]);
+
 const hostnameFromCallbackDomain = (callbackDomain: string): string | undefined => {
   const trimmed = callbackDomain.trim();
   if (trimmed.length === 0) return undefined;
@@ -327,23 +330,17 @@ const hostnameFromCallbackDomain = (callbackDomain: string): string | undefined
   if (!URL.canParse(candidate)) return undefined;
   const url = new URL(candidate);
   // A legitimate regional host carries no port, credentials, or path.
-  if (url.port !== "" || url.username !== "" || url.password !== "") return undefined;
+  if (url.protocol !== "https:" || url.port !== "" || url.username !== "" || url.password !== "") {
+    return undefined;
+  }
+  if (url.search !== "" || url.hash !== "") return undefined;
   if (url.pathname !== "/" && url.pathname !== "") return undefined;
   return url.hostname.toLowerCase();
 };
 
-/** Parent domain after stripping the leftmost DNS label, or `undefined` when
- *  the host has no sibling space (a single label, or a parent that is a bare
- *  TLD). `app.datadoghq.com` -> `datadoghq.com`; `foo.com` -> undefined. */
-const siblingParentDomainOf = (hostname: string): string | undefined => {
-  const labels = hostname.split(".");
-  if (labels.length < 3) return undefined;
-  const parent = labels.slice(1).join(".");
-  // Require the parent to itself be multi-label so a 2-label configured host
-  // can never rebind across an entire TLD (e.g. foo.com -> bar.com).
-  return parent.includes(".") ? parent : undefined;
-};
-
+/** Select a supported Datadog token host from callback data, preserving every
+ * other URL component. Untrusted or malformed callbacks leave the configured
+ * endpoint unchanged; DNS suffix similarity never grants trust. */
 export const rebindTokenEndpointHostToCallbackDomain = (
   configuredTokenUrl: string,
   callbackDomain: string | null | undefined,
@@ -351,14 +348,21 @@ export const rebindTokenEndpointHostToCallbackDomain = (
   if (!callbackDomain) return configuredTokenUrl;
   if (!URL.canParse(configuredTokenUrl)) return configuredTokenUrl;
   const configured = new URL(configuredTokenUrl);
-  if (configured.protocol !== "https:") return configuredTokenUrl;
+  if (
+    configured.protocol !== "https:" ||
+    configured.port !== "" ||
+    configured.username !== "" ||
+    configured.password !== ""
+  )
+    return configuredTokenUrl;
   const targetHost = hostnameFromCallbackDomain(callbackDomain);
   if (!targetHost) return configuredTokenUrl;
   const configuredHost = configured.hostname.toLowerCase();
   if (targetHost === configuredHost) return configuredTokenUrl;
-  const configuredParent = siblingParentDomainOf(configuredHost);
-  const targetParent = siblingParentDomainOf(targetHost);
-  if (!configuredParent || !targetParent || configuredParent !== targetParent) {
+  if (
+    !DATADOG_REGIONAL_TOKEN_HOSTS.has(configuredHost) ||
+    !DATADOG_REGIONAL_TOKEN_HOSTS.has(targetHost)
+  ) {
     return configuredTokenUrl;
   }
   const rebound = new URL(configuredTokenUrl);
@@ -366,6 +370,22 @@ export const rebindTokenEndpointHostToCallbackDomain = (
   return rebound.toString();
 };
 
+/** Parse a persisted refresh endpoint against the current client configuration.
+ * Only the configured URL or an exact supported regional substitution is
+ * accepted. Invalid legacy overrides return undefined, requiring reconnect. */
+export const tokenEndpointForRefresh = (
+  configuredTokenUrl: string,
+  persistedTokenUrl: string | null,
+): string | undefined => {
+  if (persistedTokenUrl === null || persistedTokenUrl === configuredTokenUrl) {
+    return configuredTokenUrl;
+  }
+  if (!URL.canParse(persistedTokenUrl) || !URL.canParse(configuredTokenUrl)) return undefined;
+  const persisted = new URL(persistedTokenUrl);
+  const trusted = rebindTokenEndpointHostToCallbackDomain(configuredTokenUrl, persisted.origin);
+  return new URL(trusted).href === persisted.href ? trusted : undefined;
+};
+
 // ---------------------------------------------------------------------------
 // Error mapping — `oauth4webapi`'s `process*Response` failure shapes are
 // either a WWW-Authenticate challenge or an RFC 6749 §5.2 error body,