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High, CVSS 8.7amended

Denial of service (DoS) via deformation multipart/form-data boundary

CVE-2024-53981GHSA-59g5-xgcq-4qw3

What to do

Vendor fix available. Upgrade each affected package to the fixed version on its release line (python-multipart 0.0.18), redeploy, then verify what is actually installed.

This page has no inventory attached, so it cannot say whether you are affected. A vendor fix is not proof that your deployment is fixed.

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Affected packages

Sources

Severity and exploitation
Exploitation
No confirmed exploitation recorded. Patch Next marks exploitation only from CISA KEV.
CVSS 4.0
8.7 · CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N · score source
EPSS
  • CVE-2024-53981: 0.64% estimated exploitation activity in the next 30 days; percentile 50.47 (FIRST EPSS, 2026-11-03). This is a model estimate, not proof of exploitation or customer exposure.
Source description

As published by the source; long descriptions are shortened.

Summary When parsing form data, python-multipart skips line breaks (CR \r or LF \n) in front of the first boundary and any tailing bytes after the last boundary. This happens one byte at a time and emits a log event each time, which may cause excessive logging for certain inputs. An attacker could abuse this by sending a malicious request with lots of data before the first or after the last boundary, causing high CPU load and stalling the processing thread for a significant amount of time. In case of ASGI application, this could stall the event loop and prevent other requests from being processed, resulting in a denial of service (DoS). Impact Applications that use python-multipart to parse form data (or use frameworks that do so) are affected. Original Report This security issue was reported by: - GitHub security advisory in Starlette on October 30 by @Startr4ck - Email to python-multipart maintainer on October 3 by @mnqazi

Dates and revisions
Published by the source
Last modified by the source
Source last checked
  1. Revision 3 · amended ·

    Amended from ghsa record GHSA-59g5-xgcq-4qw3

  2. Revision 2 · amended ·

    Reviewed OSV alias/range/CVSS4 correction; package source scopes and original publication preserved. No customer finding resolved.

  3. Revision 1 · created ·

    Published from osv record GHSA-59g5-xgcq-4qw3

Agent brief

Preview the exact text before you copy it. Commands are read-only suggestions; review them before running anything.

# Patch Next advisory brief: CVE-2024-53981

Advisory: Denial of service (DoS) via deformation `multipart/form-data` boundary
IDs: CVE-2024-53981, GHSA-59g5-xgcq-4qw3
Record: https://patchnext.com/advisories/cve-2024-53981 (revision 3, source checked 26 Oct 2026, 13:30 UTC)
Inventory: none attached. This brief comes from a public page and does not say whether any deployment is affected.
Severity: High (CVSS 8.7)
Exploitation: no confirmed exploitation recorded. Patch Next confirms exploitation only from CISA KEV.
Vendor response: Vendor fix available; fixed versions by package: python-multipart 0.0.18. A vendor fix does not mean a deployment is fixed.

## Affected components
- PyPI python-multipart: affected < 0.0.18; fixed in 0.0.18

## Suggested inspection (read-only)
- `python -m pip show python-multipart`: prints the installed version. Run with the environment that serves production active.

## Supported action
Upgrade each affected component to a fixed version on its release line. For a transitive dependency, upgrade the parent package or add an override or constraint, then regenerate the lockfile. Redeploy every environment that ran an affected version.

## Required regression checks
- Run the test suite and a production build.
- Exercise the features that depend on python-multipart.
- Repeat the inspection and confirm that only fixed versions remain installed.

## Rollback considerations
- Keep the previous lockfile and deployment artifact. Rolling back reinstates the vulnerable version, so apply any documented mitigation while you fix forward.

## Unresolved questions
- Which deployments run an affected version?
- Exploitation status can change. Check again before lowering the priority.
- Mark the work resolved only after the fixed version is verified in production.

## Sources
- Verified: https://osv.dev/vulnerability/GHSA-59g5-xgcq-4qw3 (OSV record GHSA-59g5-xgcq-4qw3 lists affected ranges: PyPI python-multipart >=0 <0.0.18 (fixed))
- Verified: https://github.com/advisories/GHSA-59g5-xgcq-4qw3 (GitHub-reviewed advisory GHSA-59g5-xgcq-4qw3 lists affected ranges: PyPI python-multipart >=0 <0.0.18)

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