Description
Starlette is a lightweight ASGI (Asynchronous Server Gateway Interface) framework/toolkit, designed for building async web services in Python. In versions 0.47.1 and below, when parsing a multi-part form with large files (greater than the default max spool size) starlette will block the main thread to roll the file over to disk. This blocks the event thread which means the application can't accept new connections. The UploadFile code has a minor bug where instead of just checking for self._in_memory, the logic should also check if the additional bytes will cause a rollover. The vulnerability is fixed in version 0.47.2.
CVSS breakdown
CVSS 3.1
Attack Vector
Network
Attack Complexity
Low
Privileges Required
None
User Interaction
None
Scope
Unchanged
Confidentiality
None
Integrity
None
Availability
Low
Affected products
- encode / starlette< 0.47.2 – < 0.47.2
References
- VENDOR_ADVISORYhttps://github.com/encode/starlette/security/advisories/GHSA-2c2j-9gv5-cj73
- PATCHhttps://github.com/encode/starlette/commit/9f7ec2eb512fcc3fe90b43cb9dd9e1d08696bec1
- MISChttps://github.com/encode/starlette/blob/fa5355442753f794965ae1af0f87f9fec1b9a3de/starlette/datastructures.py#L436C5-L447C14
- MISChttps://github.com/encode/starlette/discussions/2927#discussioncomment-13721403