{"cve":"CVE-2026-28356","nvd":{"published":"2026-03-12T17:16:50.080","modified":"2026-08-24T13:17:53.460","status":"Deferred","description":"multipart is a fast multipart/form-data parser for python. Prior to 1.2.2, 1.3.1 and 1.4.0-dev, the parse_options_header() function in multipart.py uses a regular expression with an ambiguous alternation, which can cause exponential backtracking (ReDoS) when parsing maliciously crafted HTTP or multipart segment headers. This can be abused for denial of service (DoS) attacks against web applications using this library to parse request headers or multipart/form-data streams. The issue is fixed in 1.2.2, 1.3.1 and 1.4.0-dev.","cvss_v4":null,"cvss_v3":{"version":"3.1","vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H","score":7.5},"cwes":["CWE-1333"],"references":["https://github.com/defnull/multipart/security/advisories/GHSA-p2m9-wcp5-6qw3","https://access.redhat.com/errata/RHSA-2026:10184","https://access.redhat.com/errata/RHSA-2026:37275","https://access.redhat.com/errata/RHSA-2026:42644","https://access.redhat.com/errata/RHSA-2026:5809"],"products":[],"source":"nvd","synced_at":"2026-10-19T22:25:53.701907451+00:00"},"epss":{"cve":"CVE-2026-28356","score":0.00762,"percentile":0.55379,"date":"2026-10-31"},"kev":null,"osv":[{"id":"GHSA-p2m9-wcp5-6qw3","url":"https://osv.dev/vulnerability/GHSA-p2m9-wcp5-6qw3","summary":"multipart vulnerable to ReDoS in `parse_options_header()`","modified":"2026-09-10T03:50:40.128718246Z","packages":[{"ecosystem":"PyPI","name":"multipart","purl":"pkg:pypi/multipart","ranges":[">=1.3.0 <1.3.1"],"fixed":["1.3.1"]},{"ecosystem":"PyPI","name":"multipart","purl":"pkg:pypi/multipart","ranges":["<1.2.2"],"fixed":["1.2.2"]}]},{"id":"PYSEC-2026-2670","url":"https://osv.dev/vulnerability/PYSEC-2026-2670","summary":"multipart vulnerable to ReDoS in `parse_options_header()`","modified":"2026-07-13T16:32:40.103985053Z","packages":[{"ecosystem":"PyPI","name":"multipart","purl":"pkg:pypi/multipart","ranges":["<1.2.2",">=1.3.0 <1.3.1"],"fixed":["1.2.2","1.3.1"]}]}],"attribution":["This product uses the NVD API but is not endorsed or certified by the NVD.","EPSS scores: FIRST Exploit Prediction Scoring System, https://www.first.org/epss","Known exploited vulnerabilities: CISA Known Exploited Vulnerabilities Catalog, https://www.cisa.gov/known-exploited-vulnerabilities-catalog","Package advisories: OSV (https://osv.dev), from the GitHub Advisory Database, PyPA, Go, RustSec and other ecosystem databases, under CC-BY 4.0 or CC0","CVE records: the CVE Program's CVE List (https://www.cve.org), under its terms of use (https://www.cve.org/Legal/TermsOfUse). CVE is a registered trademark of The MITRE Corporation; this product is not affiliated with the CVE Program."]}