{"schemaVersion":3,"id":"CVE-2026-15565","aliases":["UBUNTU-CVE-2026-15565","DEBIAN-CVE-2026-15565"],"status":"published","duplicateOf":null,"title":null,"description":"A flaw was found in Undertow. A remote attacker can cause Out of Memory on websockets endpoint without authentication on any @ServerEndpoint class that has any @OnMessage method. This allows an attacker to cause Denial of Service attack without authentication and using only a standard WebSocket handshake.","dates":{"published":"2026-08-11T08:49:58.552Z","modified":"2026-10-15T16:24:01.858Z","reserved":null,"kevAdded":[],"kevDue":[]},"cvss":{"headline":{"score":7.5,"severity":"high","version":"3.1","versionLabel":"v3.1","source":"CVE.org","vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H","computed":false,"selection":"backend-summary"},"metrics":[{"version":"3.1","versionLabel":"v3.1","source":"CVE.org","score":7.5,"severity":"high","vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H","exploitability":null,"impact":null,"computed":false},{"version":"3.1","versionLabel":"v3.1","source":"OSV · Ubuntu","score":7.5,"severity":"high","vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H","exploitability":10,"impact":6,"computed":true},{"version":"3.1","versionLabel":"v3.1","source":"OSV · Debian","score":7.5,"severity":"high","vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H","exploitability":10,"impact":6,"computed":true},{"version":"3.1","versionLabel":"v3.1","source":"NVD","score":7.5,"severity":"high","vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H","exploitability":null,"impact":null,"computed":false}]},"epss":{"probability":0.00608,"percentile":0.48075,"severity":"low","asOf":"2026-10-19T00:00:00.000Z","change":{"pp":0.098,"baselineDate":"2026-09-19T00:00:00.000Z","baselineScore":0.0051},"history":[{"date":"2026-09-14T00:00:00.000Z","score":0.0047,"percentile":null},{"date":"2026-09-15T00:00:00.000Z","score":0.0047,"percentile":null},{"date":"2026-09-16T00:00:00.000Z","score":0.0047,"percentile":null},{"date":"2026-09-17T00:00:00.000Z","score":0.0047,"percentile":null},{"date":"2026-09-18T00:00:00.000Z","score":0.0051,"percentile":null},{"date":"2026-09-19T00:00:00.000Z","score":0.0051,"percentile":null},{"date":"2026-09-20T00:00:00.000Z","score":0.0051,"percentile":null},{"date":"2026-09-21T00:00:00.000Z","score":0.0051,"percentile":null},{"date":"2026-09-22T00:00:00.000Z","score":0.0051,"percentile":null},{"date":"2026-09-23T00:00:00.000Z","score":0.00592,"percentile":null},{"date":"2026-09-24T00:00:00.000Z","score":0.00592,"percentile":null},{"date":"2026-09-25T00:00:00.000Z","score":0.00592,"percentile":null},{"date":"2026-09-26T00:00:00.000Z","score":0.00608,"percentile":null},{"date":"2026-09-27T00:00:00.000Z","score":0.00608,"percentile":null},{"date":"2026-09-28T00:00:00.000Z","score":0.00608,"percentile":null},{"date":"2026-09-29T00:00:00.000Z","score":0.00608,"percentile":null},{"date":"2026-09-30T00:00:00.000Z","score":0.00608,"percentile":null},{"date":"2026-10-01T00:00:00.000Z","score":0.00608,"percentile":null},{"date":"2026-10-02T00:00:00.000Z","score":0.00608,"percentile":null},{"date":"2026-10-03T00:00:00.000Z","score":0.00608,"percentile":null},{"date":"2026-10-04T00:00:00.000Z","score":0.00608,"percentile":null},{"date":"2026-10-05T00:00:00.000Z","score":0.00608,"percentile":null},{"date":"2026-10-06T00:00:00.000Z","score":0.00608,"percentile":null},{"date":"2026-10-07T00:00:00.000Z","score":0.00608,"percentile":null},{"date":"2026-10-08T00:00:00.000Z","score":0.00608,"percentile":null},{"date":"2026-10-09T00:00:00.000Z","score":0.00608,"percentile":null},{"date":"2026-10-10T00:00:00.000Z","score":0.00608,"percentile":null},{"date":"2026-10-11T00:00:00.000Z","score":0.00608,"percentile":null},{"date":"2026-10-12T00:00:00.000Z","score":0.00608,"percentile":null},{"date":"2026-10-13T00:00:00.000Z","score":0.00608,"percentile":null},{"date":"2026-10-14T00:00:00.000Z","score":0.00608,"percentile":null},{"date":"2026-10-15T00:00:00.000Z","score":0.00608,"percentile":null},{"date":"2026-10-16T00:00:00.000Z","score":0.00608,"percentile":null},{"date":"2026-10-17T00:00:00.000Z","score":0.00608,"percentile":null},{"date":"2026-10-18T00:00:00.000Z","score":0.00608,"percentile":null},{"date":"2026-10-19T00:00:00.000Z","score":0.00608,"percentile":0.48075}],"last30":[{"date":"2026-09-19T00:00:00.000Z","score":0.0051,"percentile":null},{"date":"2026-09-20T00:00:00.000Z","score":0.0051,"percentile":null},{"date":"2026-09-21T00:00:00.000Z","score":0.0051,"percentile":null},{"date":"2026-09-22T00:00:00.000Z","score":0.0051,"percentile":null},{"date":"2026-09-23T00:00:00.000Z","score":0.00592,"percentile":null},{"date":"2026-09-24T00:00:00.000Z","score":0.00592,"percentile":null},{"date":"2026-09-25T00:00:00.000Z","score":0.00592,"percentile":null},{"date":"2026-09-26T00:00:00.000Z","score":0.00608,"percentile":null},{"date":"2026-09-27T00:00:00.000Z","score":0.00608,"percentile":null},{"date":"2026-09-28T00:00:00.000Z","score":0.00608,"percentile":null},{"date":"2026-09-29T00:00:00.000Z","score":0.00608,"percentile":null},{"date":"2026-09-30T00:00:00.000Z","score":0.00608,"percentile":null},{"date":"2026-10-01T00:00:00.000Z","score":0.00608,"percentile":null},{"date":"2026-10-02T00:00:00.000Z","score":0.00608,"percentile":null},{"date":"2026-10-03T00:00:00.000Z","score":0.00608,"percentile":null},{"date":"2026-10-04T00:00:00.000Z","score":0.00608,"percentile":null},{"date":"2026-10-05T00:00:00.000Z","score":0.00608,"percentile":null},{"date":"2026-10-06T00:00:00.000Z","score":0.00608,"percentile":null},{"date":"2026-10-07T00:00:00.000Z","score":0.00608,"percentile":null},{"date":"2026-10-08T00:00:00.000Z","score":0.00608,"percentile":null},{"date":"2026-10-09T00:00:00.000Z","score":0.00608,"percentile":null},{"date":"2026-10-10T00:00:00.000Z","score":0.00608,"percentile":null},{"date":"2026-10-11T00:00:00.000Z","score":0.00608,"percentile":null},{"date":"2026-10-12T00:00:00.000Z","score":0.00608,"percentile":null},{"date":"2026-10-13T00:00:00.000Z","score":0.00608,"percentile":null},{"date":"2026-10-14T00:00:00.000Z","score":0.00608,"percentile":null},{"date":"2026-10-15T00:00:00.000Z","score":0.00608,"percentile":null},{"date":"2026-10-16T00:00:00.000Z","score":0.00608,"percentile":null},{"date":"2026-10-17T00:00:00.000Z","score":0.00608,"percentile":null},{"date":"2026-10-18T00:00:00.000Z","score":0.00608,"percentile":null},{"date":"2026-10-19T00:00:00.000Z","score":0.00608,"percentile":0.48075}]},"kev":{"state":"not-listed","entries":[],"listedCount":0,"totalCatalogs":3,"catalogs":[{"source":"cisa","label":"CISA","listed":false,"entry":null},{"source":"enisa","label":"ENISA","listed":false,"entry":null},{"source":"circl","label":"CIRCL","listed":false,"entry":null}]},"ransomware":{"state":"none-recorded","sources":[]},"exploits":[],"exploitCount":0,"weaknesses":[{"id":"CWE-120","name":"Buffer Copy without Checking Size of Input ('Classic Buffer Overflow')","description":"The product copies an input buffer to an output buffer without verifying that the size of the input buffer is less than the size of the output buffer.","type":"weakness","status":"Incomplete","abstraction":"Base","likelihoodOfExploit":"High","url":"https://cwe.mitre.org/data/definitions/120.html"}],"affected":[{"vendor":"debian","product":"undertow","name":"undertow","label":"undertow","ecosystem":"Debian","cpePart":null,"purl":"pkg:deb/debian/undertow","purlType":"deb","versions":[{"text":"All versions","noFixRecorded":true,"fixedIn":null}],"versionsText":"All versions (No fix recorded)","eol":null,"hubHref":null},{"vendor":"ubuntu","product":"undertow","name":"undertow","label":"undertow","ecosystem":"Ubuntu","cpePart":null,"purl":"pkg:deb/ubuntu/undertow","purlType":"deb","versions":[{"text":"All versions","noFixRecorded":true,"fixedIn":null}],"versionsText":"All versions (No fix recorded)","eol":null,"hubHref":null}],"affectedCount":2,"eol":{"hasEol":false,"count":0},"references":[{"url":"https://access.redhat.com/errata/RHSA-2026:53644","label":"access.redhat.com/errata/RHSA-2026:53644","hostname":"access.redhat.com","tags":["Vendor Advisory","X Refsource REDHAT"]},{"url":"https://access.redhat.com/errata/RHSA-2026:53645","label":"access.redhat.com/errata/RHSA-2026:53645","hostname":"access.redhat.com","tags":["Vendor Advisory","X Refsource REDHAT"]},{"url":"https://access.redhat.com/errata/RHSA-2026:53646","label":"access.redhat.com/errata/RHSA-2026:53646","hostname":"access.redhat.com","tags":["Vendor Advisory","X Refsource REDHAT"]},{"url":"https://access.redhat.com/errata/RHSA-2026:53806","label":"access.redhat.com/errata/RHSA-2026:53806","hostname":"access.redhat.com","tags":["Vendor Advisory","X Refsource REDHAT","REPORT"]},{"url":"https://access.redhat.com/errata/RHSA-2026:70228","label":"access.redhat.com/errata/RHSA-2026:70228","hostname":"access.redhat.com","tags":["Vendor Advisory","X Refsource REDHAT"]},{"url":"https://access.redhat.com/errata/RHSA-2026:70229","label":"access.redhat.com/errata/RHSA-2026:70229","hostname":"access.redhat.com","tags":["Vendor Advisory","X Refsource REDHAT"]},{"url":"https://access.redhat.com/errata/RHSA-2026:70230","label":"access.redhat.com/errata/RHSA-2026:70230","hostname":"access.redhat.com","tags":["Vendor Advisory","X Refsource REDHAT"]},{"url":"https://access.redhat.com/errata/RHSA-2026:70277","label":"access.redhat.com/errata/RHSA-2026:70277","hostname":"access.redhat.com","tags":["Vendor Advisory","X Refsource REDHAT"]},{"url":"https://access.redhat.com/security/cve/CVE-2026-15565","label":"access.redhat.com/security/cve/CVE-2026-15565","hostname":"access.redhat.com","tags":["VDB Entry","X Refsource REDHAT","REPORT"]},{"url":"https://bugzilla.redhat.com/show_bug.cgi?id=2490628","label":"bugzilla.redhat.com/show_bug.cgi?id=2490628","hostname":"bugzilla.redhat.com","tags":["Issue Tracking","X Refsource REDHAT","REPORT"]},{"url":"https://ubuntu.com/security/CVE-2026-15565","label":"ubuntu.com/security/CVE-2026-15565","hostname":"ubuntu.com","tags":["REPORT"]},{"url":"https://www.cve.org/CVERecord?id=CVE-2026-15565","label":"www.cve.org/CVERecord?id=CVE-2026-15565","hostname":"www.cve.org","tags":["REPORT"]},{"url":"https://security-tracker.debian.org/tracker/CVE-2026-15565","label":"security-tracker.debian.org/tracker/CVE-2026-15565","hostname":"security-tracker.debian.org","tags":["Advisory"]}],"lineage":{"upstream":[],"downstream":["RHSA-2026:53644","RHSA-2026:53645","RHSA-2026:53646","RHSA-2026:70228","RHSA-2026:70229","RHSA-2026:70230"],"duplicates":[],"related":[]},"timeline":[{"kind":"published","date":"2026-08-11T08:49:58.552Z","label":"Published","detail":"Vulnerability first disclosed.","source":null},{"kind":"modified","date":"2026-10-15T16:24:01.858Z","label":"Last modified","detail":"Vulnerability information updated.","source":null}],"risk":{"score":30,"level":"medium","profile":"Default","thresholds":{"critical":75,"high":50,"medium":25,"low":10}},"meta":{"dataAsOf":"2026-10-20T03:59:01.103Z","stale":false,"partial":false}}