SB2026110959 - Input validation error in python-multipart

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Main Vulnerability Database SB2026110959

SB2026110959 - Input validation error in python-multipart

Published: November 9, 2026

Security Bulletin ID SB2026110959
CSH Severity
Low
Patch available
YES
Number of vulnerabilities 1
Exploitation vector Remote access
Highest impact Partial DoS

Breakdown by Severity

Low 100%
  • Low
  • Medium
  • High
  • Critical

Description

This security bulletin contains information about 1 vulnerability.


1) Input validation error (CVE-ID: CVE-2026-53540)

CWE-ID: CWE-20 - Improper input validation

CVSSv4: 6.3 [CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:N/VI:N/VA:L/SC:N/SI:N/SA:N]


The vulnerability allows an unauthenticated remote attacker to degrade application availability through excessive request body buffering in memory.

The vulnerability exists due to missing validation of negative Content-Length values in python-multipart's parse_form() when applications call it directly with raw client headers without normalizing those values. An unauthenticated remote attacker can submit concurrent requests with negative Content-Length headers to make each request body load into memory in a single read.


Remediation

Install update from vendor's website.

References