PYSEC-2026-481: 
## Summary

**Type:** Vertical privilege escalation. The `PATCH /workspaces/{workspace_id}/members/{user_id}` endpoint is gated by `require_workspace_member(workspace_id)`, which defaults to `min_role="member"` and is never overridden by the route. The handler then calls `MemberService.update_role(workspace_id, user_id, body.role)` which sets the target member's role to whatever the request body specifies, with no check that the caller has owner-or-admin privilege, no check that the new role is not higher than the caller's own, and no check that the caller is not silently promoting themselves.
 **File:** `src/praisonai-platform/praisonai_platform/api/routes/workspaces.py`, lines 115-127; `services/member_service.py`, lines 55-69; `api/deps.py`, lines 54-73.
 **Root cause:** `require_workspace_member` exists with a `min_role` parameter (deps.py:58) but FastAPI's `Depends(require_workspace_member)` cannot pass arguments, so every route uses the default `"member"`. The route then passes the URL-supplied `user_id` and the body-supplied `role` directly to `MemberService.update_role`, which contains zero permission checks: it loads the member by composite key and assigns `member.role = new_role`. A user with the lowest possible privilege ("member") thus sets their own role to "owner" with one HTTP PATCH, completing a member-to-owner privilege escalation in a single request.

## Affected Code

**File 1:** `src/praisonai-platform/praisonai_platform/api/routes/workspaces.py`, lines 115-127.

```python
@router.patch("/{workspace_id}/members/{user_id}", response_model=MemberResponse)
async def update_member_role(
    workspace_id: str,
    user_id: str,
    body: MemberUpdate,
    user: AuthIdentity = Depends(require_workspace_member),         # <-- BUG: defaults to min_role="member"; no role gate
    session: AsyncSession = Depends(get_db),
):
    member_svc = MemberService(session)
    member = await member_svc.update_role(workspace_id, user_id, body.role)  # <-- writes any role to any member
    if member is None:
        raise HTTPException(status_code=404, detail="Member not found")
    return MemberResponse.model_validate(member)
 ```

**File 2:** `src/praisonai-platform/praisonai_platform/services/member_service.py`, lines 55-69.

```python
async def update_role(
    self,
    workspace_id: str,
    user_id: str,
    new_role: str,
) -> Optional[Member]:
    """ Update a member's role."""
    if new_role not in VALID_ROLES:                                  # only validates the *value*, not the *caller's right*
        raise ValueError(f"Invalid role: {new_role}. Must be one of {VALID_ROLES}")
    member = await self.get(workspace_id, user_id)
    if member is None:
        return None
    member.role = new_role                                           # <-- BUG: no caller-role check, no target-vs-caller hierarchy check
    await self._session.flush()
    return member
```

**File 3:** `src/praisonai-platform/praisonai_platform/api/deps.py`, lines 54-73.

```python
async def require_workspace_member(
    workspace_id: str,
    user: AuthIdentity = Depends(get_current_user),
    session: AsyncSession = Depends(get_db),
    min_role: str = "member",                                        # <-- default that no route overrides
) -> AuthIdentity:
    member_svc = MemberService(session)
    has = await member_svc.has_role(workspace_id, user.id, min_role)
    if not has:
        raise HTTPException(status_code=403, detail="Not a member of this workspace or insufficient role")
    user.workspace_id = workspace_id
    return user
```

**Why it's wrong:** `require_workspace_member` was clearly designed to be tunable per-route — the `min_role` parameter is right there — but `Depends(require_workspace_member)` in FastAPI cannot pass arguments to a dependency, so every route resolves to the default `"member"`. The author's intent is also evident in `MemberService.has_role` (member_service.py:80-96), which implements an `owner > admin > member` hierarchy that this endpoint should be enforcing. The endpoint uses none of it. The `VALID_ROLES = {"owner", "admin", "member"}` enum check (member_service.py:62) only validates the *new role string is recognised*, not that the *caller has the right to assign it*. As a result, a member can write `{"role": "owner"}` to their own membership row and become owner in one PATCH.
 
## Exploit Chain

1. Attacker registers an account and joins (or is invited to) any workspace `W` as a "member" (the lowest privilege tier — typically anyone can be added by an owner during onboarding, or self-joins via an invite link). State: attacker has a JWT, is a `Member(workspace_id=W, user_id=attacker, role="member")`.
2. Attacker sends `PATCH /workspaces/W/members/<attacker_user_id>` with `Authorization: Bearer <attacker_jwt>` and body `{"role": "owner"}`. State: control flow enters `update_member_role`.
3. `require_workspace_member(W, attacker)` runs. Its default `min_role="member"` is satisfied because the attacker is a member. The dependency returns the attacker's identity. State: route handler proceeds with no further role gate.
4. `MemberService.update_role(W, attacker, "owner")` runs. `VALID_ROLES` accepts `"owner"`. `self.get(W, attacker)` returns the attacker's existing member row. The next line, `member.role = "owner"`, mutates the attacker's role in place. `await self._session.flush()` commits. State: attacker is now `Member(workspace_id=W, user_id=attacker, role="owner")`.
5. Attacker re-issues `GET /auth/me` (or any owner-gated endpoint) and is now treated as workspace owner. State: full administrative control of the workspace, including the ability to add/remove members, change settings, delete the workspace, and exfiltrate everything via the agent/issue/project/comment IDORs that were filed as separate advisories.
6. Final state: starting from the lowest workspace privilege, the attacker holds owner of the workspace within one HTTP request. The same primitive also lets the attacker DEMOTE the legitimate owner by sending `PATCH /workspaces/W/members/<owner_user_id>` with `{"role": "member"}` — owner lockout in two requests total.

## Security Impact

**Severity:** sec-critical. CVSS 9.1: network attack, low complexity, low privileges (the lowest tier on the platform), no user interaction, scope changed (the privilege boundary the attacker crosses is the workspace owner, a different security principal), high confidentiality and integrity (full workspace control), no availability claim (the attacker can also DELETE the workspace via the companion `delete_workspace` advisory, but that is a separate finding).
**Attacker capability:** with one workspace-member token plus one PATCH request, the attacker becomes workspace owner. From there: add/remove any user as owner, change every workspace setting (including the `settings` JSON blob), demote the legitimate owner to "member", or chain into the companion `delete_workspace` advisory to wipe the workspace entirely. In multi-tenant SaaS deployments where any signup yields a member-level account in some default workspace, this is effectively pre-auth.
**Preconditions:** `praisonai-platform` is deployed multi-tenant (more than one workspace exists OR the deployment grants member access on signup); the attacker has any membership token in the target workspace.
**Differential:** source-inspection-verified end-to-end. The asymmetry between `require_workspace_member`'s `min_role` parameter (which exists, defaults to "member", and is never overridden) and `MemberService.has_role`'s clearly tiered `owner > admin > member` hierarchy (which exists but is never invoked with anything but the default) is the smoking gun. With the suggested fix below, the route resolves with `min_role="owner"`, the attacker's member-level token fails the gate at the dependency, and the privilege escalation never reaches the service layer.

## Suggested Fix

The fix has two parts. First, the route must resolve `require_workspace_member` with `min_role="owner"` (or at least `"admin"`). Second, `MemberService.update_role` should refuse to set a target's role higher than the caller's own role, so that an admin cannot accidentally produce another owner.

```diff
--- a/src/praisonai-platform/praisonai_platform/api/routes/workspaces.py
 +++ b/src/praisonai-platform/praisonai_platform/api/routes/workspaces.py
@@ -115,11 +115,16 @@
+def _require_owner(workspace_id: str, user, session):
+    return require_workspace_member(workspace_id, user, session, min_role="owner")
+
 @router.patch("/{workspace_id}/members/{user_id}", response_model=MemberResponse)
 async def update_member_role(
     workspace_id: str,
     user_id: str,
     body: MemberUpdate,
-    user: AuthIdentity = Depends(require_workspace_member),
+    user: AuthIdentity = Depends(_require_owner),
     session: AsyncSession = Depends(get_db),
 ):
     member_svc = MemberService(session)
+    if not await member_svc.has_role(workspace_id, user.id, "owner"):
+        raise HTTPException(status_code=403, detail="Only owners can change member roles")
     member = await member_svc.update_role(workspace_id, user_id, body.role)
```

Defence-in-depth in the service layer:

```diff
 --- a/src/praisonai-platform/praisonai_platform/services/member_service.py
+++ b/src/praisonai-platform/praisonai_platform/services/member_service.py
@@ -55,7 +55,7 @@
-    async def update_role(self, workspace_id: str, user_id: str, new_role: str) -> Optional[Member]:
+    async def update_role(self, workspace_id: str, caller_id: str, user_id: str, new_role: str) -> Optional[Member]:
         """Update a member's role."""
+        if not await self.has_role(workspace_id, caller_id, "owner"):
+            raise PermissionError("Only owners can update member roles")
         if new_role not in VALID_ROLES:
             raise ValueError(...)
 ```

The companion endpoints `add_member`, `remove_member`, `delete_workspace`, and `update_workspace` exhibit the same `Depends(require_workspace_member)` default-min-role pattern and are filed as their own advisories so each gets a separate CVE.
CVSS v3.1: 9.6