CVE-2026-40347: medium-severity vulnerability in Kludex python-multipart
Python-Multipart affected by Denial of Service via large multipart preamble or epilogue data
Published · Updated
E-mail alert when it lands in KEV, gets a public PoC or its score goes up.
13Vexday Risk Score
No sign of exploitation. No public exploitation artifact known so far.
ssvc Trackcvss 5.3epss 0.4%
Python-Multipart is a streaming multipart parser for Python. Versions prior to 0.0.26 have a denial of service vulnerability when parsing crafted `multipart/form-data` requests with large preamble or epilogue sections. Upgrade to version 0.0.26 or later, which skips ahead to the next boundary candidate when processing leading CR/LF data and immediately discards epilogue data after the closing boundary.
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L
Affected products
Kludex · python-multipartRelated CVEs — Kludex python-multipart
In the same product, most dangerous first.
CVE-2026-24486HIGHPython-Multipart has Arbitrary File Write via Non-Default ConfigurationEPSS 2.2%CVE-2024-24762HIGHpython-multipart vulnerable to content-type header Regular expression Denial of ServiceEPSS 1.5%CVE-2026-42561HIGHPython-Multipart: Denial of Service via unbounded multipart part headersEPSS 0.7%CVE-2024-53981HIGHpython-multipart has a Denial of service (DoS) via deformation `multipart/form-data` boundaryEPSS 0.6%CVE-2026-53539HIGHPython-Multipart: Quadratic-time querystring parsing with semicolon separators causes CPU denial of serviceEPSS 0.5%CVE-2026-53540LOWPython-Multipart: Negative Content-Length in parse_form buffers the entire body in memoryEPSS 0.3%