CVE-2025-54121

MEDIUM EPSS 40.5%
Published Jul 21, 202511mo ago · Modified Jun 17, 20262w ago
5.3 CVSS 3.1
Medium
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Published Jul 21, 2025 11mo ago
Last Modified Jun 17, 2026 2w ago

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 Details

Base Score
5.3
Exploitability
3.9
Impact
1.4
Vector string
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L
Attack Vector Network
Attack Complexity Low
Privileges Required None
User Interaction None
Scope Unchanged
Confidentiality None
Integrity None
Availability Low

Threat Intelligence

EPSS Exploit Probability
40.5% percentile
Exploit & Patch Status
No Known Exploit
No Patch Available

Weaknesses 1

CWE-770

References 4

  • github.com https://github.com/encode/starlette/blob/fa5355442753f794965ae1af0f87f9fec1b9a3de/starlette/datastructures.py#L436C5-L447C14
  • github.com https://github.com/encode/starlette/commit/9f7ec2eb512fcc3fe90b43cb9dd9e1d08696bec1
  • github.com https://github.com/encode/starlette/discussions/2927#discussioncomment-13721403
  • github.com https://github.com/encode/starlette/security/advisories/GHSA-2c2j-9gv5-cj73

Remediation

No remediation data recorded yet

Check vendor advisories and the NVD entry for patch availability.