{"id":"UBUNTU-CVE-2026-81624","details":"Undertow is a flexible performant web server used in JBoss EAP and WildFly. A flaw was found in how Undertow handles WebSocket connections. Specifically, certain configuration limits like message buffer sizes and session timeouts cannot be adjusted and default to being unlimited. This allows a remote attacker to send large amounts of data or maintain connections indefinitely, potentially crashing the server by exhausting its memory or other resources.","modified":"2026-09-02T16:28:28Z","published":"2026-08-31T09:17:00Z","upstream":["CVE-2026-81624"],"references":[{"type":"REPORT","url":"https://ubuntu.com/security/CVE-2026-81624"},{"type":"REPORT","url":"https://www.cve.org/CVERecord?id=CVE-2026-81624"},{"type":"REPORT","url":"https://bugzilla.redhat.com/show_bug.cgi?id=2524868"},{"type":"REPORT","url":"https://access.redhat.com/security/cve/CVE-2026-81624"}],"affected":[{"package":{"name":"undertow","ecosystem":"Ubuntu:Pro:16.04:LTS","purl":"pkg:deb/ubuntu/undertow?arch=source&distro=esm-apps%2Fxenial"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}],"versions":["1.3.4-1","1.3.5-1","1.3.7-1","1.3.11-1","1.3.16-1","1.3.16-1ubuntu0.1~esm1"],"ecosystem_specific":{"binaries":[{"binary_version":"1.3.16-1ubuntu0.1~esm1","binary_name":"libundertow-java"}]},"database_specific":{"source":"https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-81624.json"}},{"package":{"name":"undertow","ecosystem":"Ubuntu:Pro:18.04:LTS","purl":"pkg:deb/ubuntu/undertow?arch=source&distro=esm-apps%2Fbionic"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}],"versions":["1.4.20-1","1.4.21-1","1.4.22-1","1.4.23-1","1.4.23-2build1","1.4.23-3","1.4.23-3ubuntu0.1~esm1"],"ecosystem_specific":{"binaries":[{"binary_name":"libundertow-java","binary_version":"1.4.23-3ubuntu0.1~esm1"}]},"database_specific":{"source":"https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-81624.json"}},{"package":{"name":"undertow","ecosystem":"Ubuntu:Pro:20.04:LTS","purl":"pkg:deb/ubuntu/undertow?arch=source&distro=esm-apps%2Ffocal"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}],"versions":["2.0.23-1","2.0.27-1","2.0.28-1","2.0.29-1","2.0.29-1ubuntu0.1~esm1"],"ecosystem_specific":{"binaries":[{"binary_name":"libundertow-java","binary_version":"2.0.29-1ubuntu0.1~esm1"}]},"database_specific":{"source":"https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-81624.json"}},{"package":{"name":"undertow","ecosystem":"Ubuntu:Pro:22.04:LTS","purl":"pkg:deb/ubuntu/undertow?arch=source&distro=esm-apps%2Fjammy"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}],"versions":["2.2.8-1","2.2.12-1","2.2.13-1","2.2.14-1","2.2.16-1","2.2.16-1ubuntu0.1~esm1"],"ecosystem_specific":{"binaries":[{"binary_name":"libundertow-java","binary_version":"2.2.16-1ubuntu0.1~esm1"}]},"database_specific":{"source":"https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-81624.json"}},{"package":{"name":"undertow","ecosystem":"Ubuntu:Pro:24.04:LTS","purl":"pkg:deb/ubuntu/undertow?arch=source&distro=esm-apps%2Fnoble"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}],"versions":["2.3.8-2","2.3.8-2ubuntu0.1~esm1"],"ecosystem_specific":{"binaries":[{"binary_name":"libundertow-java","binary_version":"2.3.8-2ubuntu0.1~esm1"}]},"database_specific":{"source":"https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-81624.json"}},{"package":{"name":"undertow","ecosystem":"Ubuntu:26.04:LTS","purl":"pkg:deb/ubuntu/undertow?arch=source&distro=resolute"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}],"versions":["2.3.18-2","2.3.20-1","2.3.20-1ubuntu1"],"ecosystem_specific":{"binaries":[{"binary_name":"libundertow-java","binary_version":"2.3.20-1ubuntu1"}]},"database_specific":{"source":"https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-81624.json"}}],"schema_version":"1.9.0","severity":[{"type":"CVSS_V3","score":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H"},{"type":"Ubuntu","score":"medium"}]}