Description
A 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).
Affected products
redhat: build of apache camel for spring boot; redhat: fuse; redhat: jboss enterprise application platform; redhat: jboss enterprise application platform expansion pack; redhat: process automation; redhat: single sign-on; redhat: undertow; redhat: enterprise linux
References10
- access.redhat.com/security/cve/CVE-2025-9784 Vendor Advisory
- access.redhat.com/errata/RHSA-2025:23143
- access.redhat.com/errata/RHSA-2026:0383
- access.redhat.com/errata/RHSA-2026:0384
- access.redhat.com/errata/RHSA-2026:0386
- access.redhat.com/errata/RHSA-2026:33371
- access.redhat.com/errata/RHSA-2026:33372
- access.redhat.com/errata/RHSA-2026:3889
- access.redhat.com/errata/RHSA-2026:3891
- access.redhat.com/errata/RHSA-2026:3892
Metrics
- CVSS 3.1
-
7.5
HIGH
Score source: CNA
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H - EPSS — exploit probability
- 2% percentile: 84 · as of 8 November 2026
- CWE
- CWE-770CWE-404
Could this be exploited in your environment?
A patch closes the known hole. A penetration test shows what an attacker can still reach — with proof.