CVE-2026-42561

Python-Multipart is a streaming multipart parser for Python. Prior to 0.0.27, 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 repeated headers without terminating the header block or a single very large header value, causing excessive CPU work before request rejection or completion. This vulnerability is fixed in 0.0.27.

Database specific

{
    "cna_assigner": "GitHub_M",
    "cwe_ids": [
        "CWE-770"
    ],
    "osv_generated_from": "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/42xxx/CVE-2026-42561.json"
}

References

Affected packages

Git / github.com/kludex/python-multipart

Affected ranges

Type

GIT

Repo

https://github.com/kludex/python-multipart

Events

Introduced

Fixed

6d1d6892a6b01b25da6f3e7b097e8e06c57fb250

Database specific

{
    "source": "AFFECTED_FIELD",
    "extracted_events": [
        {
            "introduced": "0"
        },
        {
            "fixed": "0.0.27"
        }
    ]
}

Affected versions

0.*

0.0.10

0.0.11

0.0.12

0.0.13

0.0.14

0.0.15

0.0.16

0.0.17

0.0.18

0.0.19

0.0.2

0.0.20

0.0.21

0.0.22

0.0.23

0.0.24

0.0.25

0.0.26

0.0.4

0.0.5

0.0.6

0.0.7

0.0.8

0.0.9

Database specific

source

"https://storage.googleapis.com/osv-test-cve-osv-conversion/osv-output/CVE-2026-42561.json"