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.

The remote Debian 12 / 13 host has a package installed that is affected by multiple vulnerabilities as referenced in the dsa-6302 advisory.

    - -------------------------------------------------------------------------     Debian Security Advisory DSA-6302-1                   security@debian.org     https://www.debian.org/security/                       Moritz Muehlenhoff     May 27, 2026                          https://www.debian.org/security/faq
    - -------------------------------------------------------------------------

    Package        : starlette     CVE ID         : CVE-2026-48710

    It was discovered that missing validation of Host: headers in the     Starlette ASGI framework could result in a bypass of security checks.

    For the oldstable distribution (bookworm), this problem has been fixed     in version 0.26.1-1+deb12u1. This update also resolves three additional     security issues (CVE-2023-29159, CVE-2024-47874 and CVE-2025-54121).

    For the stable distribution (trixie), this problem has been fixed in     version 0.46.1-3+deb13u2.

    We recommend that you upgrade your starlette packages.

    For the detailed security status of starlette please refer to     its security tracker page at:
    https://security-tracker.debian.org/tracker/starlette

    Further information about Debian Security Advisories, how to apply     these updates to your system and frequently asked questions can be     found at: https://www.debian.org/security/

    Mailing list: debian-security-announce@lists.debian.org

Tenable has extracted the preceding description block directly from the Debian security advisory.

Note that Nessus has not tested for these issues but has instead relied only on the application's self-reported version number.

The Linux/Unix host has one or more packages installed that are impacted by a vulnerability without a vendor supplied patch available.

  - 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.
    (CVE-2025-54121)

Note that Nessus relies on the presence of the package as reported by the vendor.

The remote openSUSE 15 host has a package installed that is affected by a vulnerability as referenced in the SUSE- SU-2025:02544-1 advisory.

    - CVE-2025-54121: Correctly parse multi-part form with large files to avoid DoS. (bsc#1246855)

Tenable has extracted the preceding description block directly from the SUSE security advisory.

Note that Nessus has not tested for this issue but has instead relied only on the application's self-reported version number.

There are packages installed that are affected by a vulnerability referenced in the following CVE:

  - 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.
    (CVE-2025-54121)

ID	Name	Product	Family	Type	Severity
317342	Debian dsa-6302 : python3-starlette - security update	Nessus	Debian Local Security Checks	Local	high
247479	Linux Distros Unpatched Vulnerability : CVE-2025-54121	Nessus	Misc.	Local	medium
243010	openSUSE 15 Security Update : python-starlette (SUSE-SU-2025:02544-1)	Nessus	SuSE Local Security Checks	Local	medium
428598	SCA: security update for starlette (GHSA-2c2j-9gv5-cj73)	Tenable Cloud Security	SCA Checks	Local	medium
428598	SCA: security update for starlette (GHSA-2c2j-9gv5-cj73)	Tenable Self-Hosted Container Security	SCA Checks	Local	medium

Detections

Analytics

CVE-2025-54121

medium

Tenable Plugins

high

medium

medium

medium

medium