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.
{
"cna_assigner": "GitHub_M",
"cwe_ids": [
"CWE-400",
"CWE-834"
],
"osv_generated_from": "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/40xxx/CVE-2026-40347.json"
}{
"extracted_events": [
{
"range": [
{
"introduced": "0"
},
{
"fixed": "0.0.26"
}
],
"source": "AFFECTED_FIELD",
"strategy": "StringRangeExpression"
},
{
"original_tag": "0.0.26",
"range": [
{
"fixed": "28f47859b4a40c2e11e02dc514b2e9743ceedd2e"
}
],
"source": "REFERENCES_TAG"
},
{
"cpe": "cpe:2.3:a:fastapiexpert:python-multipart:*:*:*:*:*:python:*:*",
"range": [
{
"introduced": "0"
},
{
"fixed": "0.0.26"
}
],
"source": "CPE_RANGE"
}
]
}