Vulnerability Report

CVE-2026-53540

Title: Python-Multipart DoS via Negative Content-Length

DoS

Proof Of Concept

No public PoC currently indexed for CVE-2026-53540.

CWE Category CWE-1284
Published Date Jun 22, 2026
Modified Date Jun 26, 2026
Exploit Status Not Found
Score 3.7 CVSS v3.1
Exploit Probability (EPSS)
0.22%

Vulnerability Summary

CVE-2026-53540: Python-Multipart is a streaming multipart parser for Python. Prior to 0.0.31, parse_form() 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 into memory in a single read instead of in fixed-size chunks. This vulnerability is fixed in 0.0.31.

Impacted Vendors

F
fastapiexpert 1

Reference Links

https://github.com/Kludex/python-multipart/security/advisories/GHSA-v9pg-7xvm-68hf
CVSS v3.1
Source Entity [email protected]
Severity LOW
3.7
Attack Vector
NETWORK
Complexity
HIGH
Privileges
N/A
Interaction
NONE
Confidentiality
N/A
Integrity
N/A
Availability
N/A
Scope
UNCHANGED
RAW VECTOR CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:L

Associated Attack Patterns (CAPEC)

Total: Patterns

CVE-2026-53540 Exploits & PoCs (Proof Of Concept)

No public PoCs found in our database for this CVE.

MODIFIED

Vulnerability data updated via NVD.

MODIFIED

Vulnerability data updated via NVD.

MODIFIED

Vulnerability data updated via NVD.

MODIFIED

Vulnerability data updated via NVD.

Attack Vector Matrix

Access Vector NETWORK
Complexity HIGH
Privileges N/A
Interaction NONE
CVSS Vector String CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:L

Affected Stack

No specific products linked.