CVE-2026-28525 HIGH

CVE-2026-28525: SWUpdate Integer Underflow in Multipart Upload Parser

Vendor Sbabic
Product swupdate
Weakness CWE-191
Published April 23, 2026
Last update May 25, 2026

CVSS base score

8.2/10
Attack vector Network
Attack complexity High
Privileges required None
User interaction None
Confidentiality
Integrity

CVSS vector

CVSS:4.0/AV:N/AC:H/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N

What the vulnerability does

01Description

SWUpdate contains an integer underflow vulnerability in the multipart upload parser in mongoose_multipart.c that allows unauthenticated attackers to cause a denial of service by sending a crafted HTTP POST request to /upload with a malformed multipart boundary and controlled TCP stream timing. Attackers can trigger an integer underflow in the mg_http_multipart_continue_wait_for_chunk() function when the buffer length falls within a specific range, causing an out-of-bounds heap read past the allocated receive buffer to a local IPC socket.

Key dates

02Disclosure timeline

April 23, 2026 CVE published
May 25, 2026 Record updated