CVE-2026-28525

Name	CVE-2026-28525
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.
Source	CVE (at NVD; CERT, ENISA, LWN, oss-sec, fulldisc, Debian ELTS, Red Hat, Ubuntu, Gentoo, SUSE bugzilla/CVE, GitHub advisories/code/issues, web search, more)

Vulnerable and fixed packages

The table below lists information on source packages.

Source Package	Release	Version	Status
swupdate (PTS)	bullseye	2020.11-2+deb11u1	vulnerable
	bookworm	2022.12+dfsg-4+deb12u1	vulnerable
	trixie	2024.12.1+dfsg-3+deb13u1	vulnerable
	forky	2025.12+dfsg-8	vulnerable
	sid	2025.12+dfsg-10	fixed

The information below is based on the following data on fixed versions.

Package	Type	Release	Fixed Version	Urgency	Origin	Debian Bugs
swupdate	source	(unstable)	2025.12+dfsg-9

Notes

[trixie] - swupdate <no-dsa> (Minor issue)
[bookworm] - swupdate <no-dsa> (Minor issue)
[bullseye] - swupdate <postponed> (Minor issue; can be fixed in next update)
Fixed by: https://github.com/sbabic/swupdate/commit/beee2dc0feef1cfe84f1aa6fc980e104b2e47a74