Excessive Iteration in python-multipart - CVE-2026-40347
Published: April 14, 2026
Vulnerability identifier: #VU125974
CSH Severity: Medium
CVSS v4: 6.9 [CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:L/SC:N/SI:N/SA:N]
CVE-ID: CVE-2026-40347
CWE-ID: CWE-834
Exploitation vector: Remote access
Exploit availability:
No public exploit available
Vulnerability details
The vulnerability allows a remote attacker to cause a denial of service.
The vulnerability exists due to excessive iteration in multipart/form-data parsing when processing crafted multipart/form-data requests with large preamble or epilogue sections. A remote attacker can send an oversized malformed multipart body to cause a denial of service.
The issue degrades availability by consuming excessive CPU time during request parsing and delaying legitimate requests, but it does not typically result in a complete denial of service for the entire application.
Affected software
python-multipart
openSUSE Leap
python311-python-multipart
openSUSE Leap
python311-python-multipart
How to mitigate CVE-2026-40347
Install security update from vendor's website.
python-multipart - update to 0.0.26
python311-python-multipart - update to 0.0.9-150600.3.9.1
python311-python-multipart - update to 0.0.9-150600.3.9.1