Vulnerability · Published Apr 23, 2026 · Assigned by VulnCheck
CVE-2026-28525SWUpdate Integer Underflow in Multipart Upload Parser
Medium 6.8
In plain English
A medium-severity out-of-bounds read in swupdate from sbabic. There are no confirmed reports of exploitation so far. The chance it is exploited in the next 30 days is estimated at 0.3% (higher than 25% of all known vulnerabilities). Fixed versions are available - upgrade the affected package.
Official 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 packages & fixed versions
| Ecosystem | Package | Fixed in | Advisory |
|---|---|---|---|
| Debian:12 | swupdate | 2022.12+dfsg-4+deb12u2 | DEBIAN-CVE-2026-28525 |
| Debian:13 | swupdate | 2024.12.1+dfsg-3+deb13u2 | DEBIAN-CVE-2026-28525 |
| Debian:14 | swupdate | 2025.12+dfsg-9 | DEBIAN-CVE-2026-28525 |
| Ubuntu:22.04:LTS | swupdate | no fix listed | UBUNTU-CVE-2026-28525 |
| Ubuntu:24.04:LTS | swupdate | no fix listed | UBUNTU-CVE-2026-28525 |
| Ubuntu:25.10 | swupdate | no fix listed | UBUNTU-CVE-2026-28525 |
| Ubuntu:26.04:LTS | swupdate | no fix listed | UBUNTU-CVE-2026-28525 |
| Ubuntu:26.10 | swupdate | no fix listed | UBUNTU-CVE-2026-28525 |
Affected products (as reported)
Weakness: CWE-191, CWE-125 · Vector: CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:C/C:N/I:N/A:H