What’s Vulnerable › Vulnerabilities

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

• Severity: medium (CVSS 6.8 v3.1)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 0.3% probability of exploitation in the next 30 days
• Public exploit or detection template: none known
• Published: 2026-04-23 · updated 2026-10-26
• Weakness: CWE-125

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 past the allocated receive buffer to a local IPC socket.

Affected products

• sbabic swupdate: through 2025.12

References

• https://github.com/sbabic/swupdate/commit/beee2dc0feef1cfe84f1aa6fc980e104b2e47a74
• https://www.vulncheck.com/advisories/swupdate-integer-underflow-in-multipart-upload-parser

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