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 that writes data beyond the allocated receive buffer to a local IPC socket.
https://www.vulncheck.com/advisories/swupdate-integer-underflow-in-multipart-upload-parser
https://github.com/sbabic/swupdate/commit/beee2dc0feef1cfe84f1aa6fc980e104b2e47a74
Published: 2026-04-23
Updated: 2026-04-23
Base Score: 5.4
Vector: CVSS2#AV:N/AC:H/Au:N/C:N/I:N/A:C
Severity: Medium
Base Score: 6.8
Vector: CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:C/C:N/I:N/A:H
Severity: Medium
Base Score: 8.2
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
Severity: High