What’s Vulnerable › Vulnerabilities

CVE-2024-53981: python-multipart has a Denial of service (DoS) via deformation `multipart/form-data` boundary

• Severity: high (CVSS 7.5 v3.1)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 0.6% probability of exploitation in the next 30 days
• Public exploit or detection template: none known
• Published: 2024-12-02 · updated 2026-06-17
• Weakness: CWE-770

Description

python-multipart is a streaming multipart parser for Python. 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). This vulnerability is fixed in 0.0.18.

Affected products

• Kludex Python-Multipart: before 0.0.18 — fixed in 0.0.18

How to fix

Upgrade to a fixed version: Kludex Python-Multipart 0.0.18. Check the vendor advisory for mitigations.

References

• https://github.com/Kludex/python-multipart/commit/c4fe4d3cebc08c660e57dd709af1ffa7059b3177
• https://github.com/Kludex/python-multipart/security/advisories/GHSA-59g5-xgcq-4qw3

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