CVE-2025-9784

NameCVE-2025-9784
DescriptionA flaw was found in Undertow where malformed client requests can trigger server-side stream resets without triggering abuse counters. This issue, referred to as the "MadeYouReset" attack, allows malicious clients to induce excessive server workload by repeatedly causing server-side stream aborts. While not a protocol bug, this highlights a common implementation weakness that can be exploited to cause a denial of service (DoS).
SourceCVE (at NVD; CERT, ENISA, LWN, oss-sec, fulldisc, Debian ELTS, Red Hat, Ubuntu, Gentoo, SUSE bugzilla/CVE, GitHub advisories/code/issues, web search, more)
Debian Bugs1117694

Vulnerable and fixed packages

The table below lists information on source packages.

Source PackageReleaseVersionStatus
undertow (PTS)forky, sid2.3.20-1fixed

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

PackageTypeReleaseFixed VersionUrgencyOriginDebian Bugs
undertowsource(unstable)2.3.20-11117694

Notes

https://bugzilla.redhat.com/show_bug.cgi?id=2392306
https://issues.redhat.com/browse/UNDERTOW-2598
Dedicated CVE for undertow for the "MadeYouReset" DoS attack
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