What’s Vulnerable › Vulnerabilities
CVE-2026-53540: Python-Multipart: Negative Content-Length in parse_form buffers the entire body in memory
- Severity: low (CVSS 3.7 v3.1)
- Exploited in the wild: not listed in CISA KEV
- EPSS: 0.3% probability of exploitation in the next 30 days
- Public exploit or detection template: none known
- Published: 2026-06-22 · updated 2026-10-25
- Weakness: CWE-1284
Description
Python-Multipart is a streaming multipart parser for Python. Prior to 0.0.31, parse_form() did not validate the Content-Length header before using it to bound its chunked read of the request body. A negative Content-Length turned the bounded read into a read-until-EOF, so the entire body was loaded into memory in a single read instead of in fixed-size chunks. This vulnerability is fixed in 0.0.31.
Affected products
- Kludex python-multipart: before 0.0.31 — fixed in 0.0.31
How to fix
Upgrade to a fixed version: Kludex python-multipart 0.0.31. Check the vendor advisory for mitigations.
References
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