CVE-2026-53539

A flaw was found in Python-Multipart, a streaming multipart parser. A remote attacker can exploit this vulnerability by submitting a specially crafted application/x-www-form-urlencoded body. This can cause the QuerystringParser to perform inefficient processing, leading to excessive CPU...

PYSEC-2026-3036 python-multipart: Quadratic-time querystring parsing with semicolon separators causes CPU denial of service

Summary When parsing application/x-www-form-urlencoded bodies, QuerystringParser located the field separator with a two step lookup: it first scanned the entire remaining buffer for &, and only when no & existed anywhere ahead did it fall back to scanning for ;. For a body that uses ; as the...

PYSEC-2026-3037 python-multipart: Semicolon treated as querystring field separator enables parameter smuggling

Summary QuerystringParser treated ; as a field separator in application/x-www-form-urlencoded bodies, in addition to &. The WHATWG URL standard, modern browsers, and Python's urllib.parse since the CVE-2021-23336 fix treat only & as a separator. This creates a parser differential: the same bytes...

PYSEC-2026-3039 python-multipart has Denial of Service via unbounded multipart part headers

Summary python-multipart has a denial of service vulnerability in multipart part header parsing. When parsing multipart/form-data, MultipartParser previously had no limit on the number of part headers or the size of an individual part header. An attacker could send a request with either many...

PYSEC-2026-3038 python-multipart affected by Denial of Service via large multipart preamble or epilogue data

Summary A denial of service vulnerability exists when parsing crafted multipart/form-data requests with large preamble or epilogue sections. Details Two inefficient multipart parsing paths could be abused with attacker-controlled input. Before the first multipart boundary, the parser handled...

CVE-2026-53538

A flaw was found in Python-Multipart, a tool used for processing web form data. A remote attacker could exploit a vulnerability where the software incorrectly interprets certain characters as separators in web form data. This difference in interpretation compared to standard web practices allows ...

PYSEC-2026-1852 Python-Multipart has Arbitrary File Write via Non-Default Configuration

Summary A Path Traversal vulnerability exists when using non-default configuration options UPLOADDIR and UPLOADKEEPFILENAME=True. An attacker can write uploaded files to arbitrary locations on the filesystem by crafting a malicious filename. Details When UPLOADDIR is set and UPLOADKEEPFILENAME is...

PYSEC-2026-1851 Denial of service (DoS) via deformation `multipart/form-data` boundary

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...

PYSEC-2026-1850 python-multipart vulnerable to Content-Type Header ReDoS

Summary When using form data, python-multipart uses a Regular Expression to parse the HTTP Content-Type header, including options. An attacker could send a custom-made Content-Type option that is very difficult for the RegEx to process, consuming CPU resources and stalling indefinitely minutes or...

ROOT-APP-PYPI-CVE-2026-42561 CVE-2026-42561 in rootio-python-multipart - Patched by Root

Root has patched CVE-2026-42561 in the rootio-python-multipart package for Root:PyPI. Multiple fixed versions available...

CVE-2026-53540

A flaw was found in python-multipart where parseform did not validate the Content-Length header before using it to bound its chunked read of the request body. A negative Content-Length turns the bounded read into a read-until-EOF, loading the entire body into memory in a single operation instead ...

CVE-2026-53537

A flaw was found in Python-Multipart. This vulnerability allows a remote attacker to bypass security controls by exploiting a difference in how Content-Disposition and Content-Type headers are parsed. Specifically, the parseoptionsheader function incorrectly applies RFC 2231/5987 decoding, which ...

Linux Distros Unpatched Vulnerability : CVE-2026-53540

The Linux/Unix host has one or more packages installed that are impacted by a vulnerability without a vendor supplied patch available. - Python-Multipart is a streaming multipart parser for Python. Prior to 0.0.31, parseform did not validate the Content-Length header before using it to bound its...

Linux Distros Unpatched Vulnerability : CVE-2026-53539

The Linux/Unix host has one or more packages installed that are impacted by a vulnerability without a vendor supplied patch available. - Python-Multipart is a streaming multipart parser for Python. Prior to 0.0.30, when parsing application/x-www-form-urlencoded bodies, QuerystringParser located t...

Linux Distros Unpatched Vulnerability : CVE-2026-53537

The Linux/Unix host has one or more packages installed that are impacted by a vulnerability without a vendor supplied patch available. - Python-Multipart is a streaming multipart parser for Python. Prior to 0.0.30, parseoptionsheader parsed Content-Disposition and Content-Type headers with...

Linux Distros Unpatched Vulnerability : CVE-2026-53538

The Linux/Unix host has one or more packages installed that are impacted by a vulnerability without a vendor supplied patch available. - Python-Multipart is a streaming multipart parser for Python. Prior to 0.0.30, QuerystringParser treated ; as a field separator in...

CVE-2026-53540

Python-Multipart is a streaming multipart parser for Python. Prior to 0.0.31, parseform 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...

CVE-2026-53537

Python-Multipart is a streaming multipart parser for Python. Prior to 0.0.30, parseoptionsheader parsed Content-Disposition and Content-Type headers with email.message.Message, which transparently applies RFC 2231/5987 decoding. The extended parameter syntax filename=charset'lang'value, name=...,...

CVE-2026-53539

Python-Multipart is a streaming multipart parser for Python. Prior to 0.0.30, when parsing application/x-www-form-urlencoded bodies, QuerystringParser located the field separator with a two step lookup: it first scanned the entire remaining buffer for &, and only when no & existed anywhere ahead...

CVE-2026-53538

Python-Multipart is a streaming multipart parser for Python. Prior to 0.0.30, QuerystringParser treated ; as a field separator in application/x-www-form-urlencoded bodies, in addition to &. The WHATWG URL standard, modern browsers, and Python's urllib.parse since the CVE-2021-23336 fix treat only...