diff --git a/src/sentry/issues/services/issue/impl.py b/src/sentry/issues/services/issue/impl.py
index 76c93b243a411f..075c2b38420be3 100644
--- a/src/sentry/issues/services/issue/impl.py
+++ b/src/sentry/issues/services/issue/impl.py
@@ -81,12 +81,14 @@ def get_shared_for_org(self, *, slug: str, share_id: str) -> RpcGroupShareMetada
             organization = Organization.objects.get(slug=slug)
         except Organization.DoesNotExist:
             return None
-        if organization.flags.disable_shared_issues:
-            return None
         try:
             group = Group.objects.from_share_id(share_id)
         except Group.DoesNotExist:
             return None
+        if group.project.organization_id != organization.id:
+            return None
+        if group.organization.flags.disable_shared_issues:
+            return None
 
         return RpcGroupShareMetadata(title=group.title, message=group.message)
 
diff --git a/tests/sentry/issues/services/__init__.py b/tests/sentry/issues/services/__init__.py
new file mode 100644
index 00000000000000..e69de29bb2d1d6
diff --git a/tests/sentry/issues/services/issue/__init__.py b/tests/sentry/issues/services/issue/__init__.py
new file mode 100644
index 00000000000000..e69de29bb2d1d6
diff --git a/tests/sentry/issues/services/issue/test_impl.py b/tests/sentry/issues/services/issue/test_impl.py
new file mode 100644
index 00000000000000..1f58f0dfbdfe95
--- /dev/null
+++ b/tests/sentry/issues/services/issue/test_impl.py
@@ -0,0 +1,58 @@
+from sentry.issues.services.issue.impl import DatabaseBackedIssueService
+from sentry.models.groupshare import GroupShare
+from sentry.testutils.cases import TestCase
+from sentry.testutils.silo import cell_silo_test
+
+
+@cell_silo_test
+class GetSharedForOrgTest(TestCase):
+    def setUp(self) -> None:
+        self.service = DatabaseBackedIssueService()
+        self.group = self.create_group(project=self.project)
+        self.share = GroupShare.objects.create(
+            project=self.group.project,
+            group=self.group,
+            user_id=self.user.id,
+        )
+
+    def test_returns_metadata_when_sharing_enabled(self) -> None:
+        result = self.service.get_shared_for_org(
+            slug=self.organization.slug, share_id=str(self.share.uuid)
+        )
+        assert result is not None
+        assert result.title == self.group.title
+
+    def test_returns_none_when_sharing_disabled_on_owner_org(self) -> None:
+        self.organization.flags.disable_shared_issues = True
+        self.organization.save()
+        result = self.service.get_shared_for_org(
+            slug=self.organization.slug, share_id=str(self.share.uuid)
+        )
+        assert result is None
+
+    def test_returns_none_when_slug_does_not_match_share_owner(self) -> None:
+        # The share UUID belongs to self.organization, but the request uses a different org's slug.
+        # This is the cross-org bypass: must be rejected regardless of the other org's flag.
+        other_org = self.create_organization(name="Other Org")
+        result = self.service.get_shared_for_org(slug=other_org.slug, share_id=str(self.share.uuid))
+        assert result is None
+
+    def test_returns_none_when_slug_mismatch_and_owner_has_sharing_disabled(self) -> None:
+        # Org A (owner) has disabled sharing. Attacker uses org B's slug with org A's share UUID.
+        self.organization.flags.disable_shared_issues = True
+        self.organization.save()
+        other_org = self.create_organization(name="Other Org")
+        result = self.service.get_shared_for_org(slug=other_org.slug, share_id=str(self.share.uuid))
+        assert result is None
+
+    def test_returns_none_for_unknown_slug(self) -> None:
+        result = self.service.get_shared_for_org(
+            slug="nonexistent-org", share_id=str(self.share.uuid)
+        )
+        assert result is None
+
+    def test_returns_none_for_unknown_share_id(self) -> None:
+        result = self.service.get_shared_for_org(
+            slug=self.organization.slug, share_id="00000000-0000-0000-0000-000000000000"
+        )
+        assert result is None