# CVE-2025-54121: starlette: Starlette is a lightweight ASGI (Asynchronous Server Gateway Interface) framework/toolkit, designed for building asyn...

CVE-2025-54121 is fixed in 2 products on 1 platform, first by DEBIAN-CVE-2025-54121, released July 21, 2025. It is not reported as exploited. Patch Radar priority: Routine.

- Web page: https://patchblox.com/security/cve/CVE-2025-54121
- Priority: Routine
- CVSS: 5.3 (medium)
- EPSS: 0.0066
- CISA KEV: not listed
- Exploited (vendor report): no
- Publicly disclosed: no
- Published: Jul 21, 2025

## 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.

## Where it's fixed

| Platform | Product | Fixed in | Fix | Released |
|---|---|---|---|---|
| Linux | python-starlette opensuse-leap 15.6 | 0.35.1-150600.3.6.1 | [SUSE-SU-2025:02544-1](https://patchblox.com/security/data/fix/linux/suse-su-2025-02544-1.md) | Jul 29, 2025 |
| Linux | python-starlette opensuse-leap 16.0 | 0.41.3-160000.3.1 | [OPENSUSE-SU-2026:20975-1](https://patchblox.com/security/data/fix/linux/opensuse-su-2026-20975-1.md) | Jun 17, 2026 |
| Linux | python-starlette sles 16.0 | 0.41.3-160000.3.1 | [SUSE-SU-2026:22151-1](https://patchblox.com/security/data/fix/linux/suse-su-2026-22151-1.md) | Jun 17, 2026 |
| Linux | starlette Debian 12.15 (bookworm) | 0.26.1-1+deb12u1 | [DEBIAN-CVE-2025-54121](https://patchblox.com/security/data/fix/linux/debian-cve-2025-54121.md) | Jul 21, 2025 |
| Linux | starlette Debian 13.5 (trixie) | 0.46.1-3 | [DEBIAN-CVE-2025-54121](https://patchblox.com/security/data/fix/linux/debian-cve-2025-54121.md) | Jul 21, 2025 |
| Linux | starlette Debian 14 | 0.46.1-3 | [DEBIAN-CVE-2025-54121](https://patchblox.com/security/data/fix/linux/debian-cve-2025-54121.md) | Jul 21, 2025 |

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Data as of 2026-11-08T19:12:23Z UTC. Source: Patchblox Patch Radar (https://patchblox.com/security/patch-radar). Patchblox finds out-of-date software on Windows, macOS and Linux and updates it through release rings: https://patchblox.com/demo

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