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Description

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.

PUBLISHED Reserved 2026-02-27 | Published 2026-04-23 | Updated 2026-04-25 | Assigner VulnCheck




HIGH: 8.2CVSS:4.0/AV:N/AC:H/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N

MEDIUM: 6.8CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:C/C:N/I:N/A:H

Problem types

CWE-191 Integer Underflow (Wrap or Wraparound)

CWE-125 Out-of-bounds Read

Product status

Default status
unaffected

Any version
affected

beee2dc0feef1cfe84f1aa6fc980e104b2e47a74 (git)
unaffected

Credits

Kazuma Matsumoto, a security researcher at GMO Cybersecurity by IERAE, Inc. finder

VulnCheck coordinator

References

github.com/...ommit/beee2dc0feef1cfe84f1aa6fc980e104b2e47a74 patch

www.vulncheck.com/...er-underflow-in-multipart-upload-parser third-party-advisory

cve.org (CVE-2026-28525)

nvd.nist.gov (CVE-2026-28525)

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