{"schemaVersion":3,"id":"CVE-2026-59843","aliases":["UBUNTU-CVE-2026-59843","DEBIAN-CVE-2026-59843","CGA-34wp-g234-fw29","CGA-6w9g-wx59-2vqx","CGA-8w5c-xq5r-fw6g","CGA-f365-39xq-qr8r","CGA-g82x-69qm-95wg","CGA-hqgx-xj9w-3498"],"status":"published","duplicateOf":null,"title":null,"description":"A flaw was found in libssh. A remote authenticated peer can advertise a zero maximum packet size in SSH_MSG_CHANNEL_OPEN, causing later channel writes to loop indefinitely and consume CPU, leading to denial of service.","dates":{"published":"2026-07-21T11:16:12.061Z","modified":"2026-09-01T20:01:39.685Z","reserved":null,"kevAdded":[],"kevDue":[]},"cvss":{"headline":{"score":6.5,"severity":"medium","version":"3.1","versionLabel":"v3.1","source":"CVE.org","vector":"CVSS:3.1/AV:N/AC:L/PR:L/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":6.5,"severity":"medium","vector":"CVSS:3.1/AV:N/AC:L/PR:L/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":6.5,"severity":"medium","vector":"CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H","exploitability":7.2,"impact":6,"computed":true},{"version":"3.1","versionLabel":"v3.1","source":"OSV · Debian","score":6.5,"severity":"medium","vector":"CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H","exploitability":7.2,"impact":6,"computed":true},{"version":"3.1","versionLabel":"v3.1","source":"NVD","score":6.5,"severity":"medium","vector":"CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H","exploitability":null,"impact":null,"computed":false}]},"epss":{"probability":0.00725,"percentile":0.53252,"severity":"low","asOf":"2026-10-19T00:00:00.000Z","change":{"pp":0.15800000000000006,"baselineDate":"2026-09-19T00:00:00.000Z","baselineScore":0.00567},"history":[{"date":"2026-09-14T00:00:00.000Z","score":0.00567,"percentile":null},{"date":"2026-09-15T00:00:00.000Z","score":0.00567,"percentile":null},{"date":"2026-09-16T00:00:00.000Z","score":0.00567,"percentile":null},{"date":"2026-09-17T00:00:00.000Z","score":0.00567,"percentile":null},{"date":"2026-09-18T00:00:00.000Z","score":0.00567,"percentile":null},{"date":"2026-09-19T00:00:00.000Z","score":0.00567,"percentile":null},{"date":"2026-09-20T00:00:00.000Z","score":0.00567,"percentile":null},{"date":"2026-09-21T00:00:00.000Z","score":0.00567,"percentile":null},{"date":"2026-09-22T00:00:00.000Z","score":0.00567,"percentile":null},{"date":"2026-09-23T00:00:00.000Z","score":0.00567,"percentile":null},{"date":"2026-09-24T00:00:00.000Z","score":0.00725,"percentile":null},{"date":"2026-09-25T00:00:00.000Z","score":0.00725,"percentile":null},{"date":"2026-09-26T00:00:00.000Z","score":0.00725,"percentile":null},{"date":"2026-09-27T00:00:00.000Z","score":0.00725,"percentile":null},{"date":"2026-09-28T00:00:00.000Z","score":0.00725,"percentile":null},{"date":"2026-09-29T00:00:00.000Z","score":0.00725,"percentile":null},{"date":"2026-09-30T00:00:00.000Z","score":0.00725,"percentile":null},{"date":"2026-10-01T00:00:00.000Z","score":0.00725,"percentile":null},{"date":"2026-10-02T00:00:00.000Z","score":0.00725,"percentile":null},{"date":"2026-10-03T00:00:00.000Z","score":0.00725,"percentile":null},{"date":"2026-10-04T00:00:00.000Z","score":0.00725,"percentile":null},{"date":"2026-10-05T00:00:00.000Z","score":0.00725,"percentile":null},{"date":"2026-10-06T00:00:00.000Z","score":0.00725,"percentile":null},{"date":"2026-10-07T00:00:00.000Z","score":0.00725,"percentile":null},{"date":"2026-10-08T00:00:00.000Z","score":0.00725,"percentile":null},{"date":"2026-10-09T00:00:00.000Z","score":0.00725,"percentile":null},{"date":"2026-10-10T00:00:00.000Z","score":0.00725,"percentile":null},{"date":"2026-10-11T00:00:00.000Z","score":0.00725,"percentile":null},{"date":"2026-10-12T00:00:00.000Z","score":0.00725,"percentile":null},{"date":"2026-10-13T00:00:00.000Z","score":0.00725,"percentile":null},{"date":"2026-10-14T00:00:00.000Z","score":0.00725,"percentile":null},{"date":"2026-10-15T00:00:00.000Z","score":0.00725,"percentile":null},{"date":"2026-10-16T00:00:00.000Z","score":0.00725,"percentile":null},{"date":"2026-10-17T00:00:00.000Z","score":0.00725,"percentile":null},{"date":"2026-10-18T00:00:00.000Z","score":0.00725,"percentile":null},{"date":"2026-10-19T00:00:00.000Z","score":0.00725,"percentile":0.53252}],"last30":[{"date":"2026-09-19T00:00:00.000Z","score":0.00567,"percentile":null},{"date":"2026-09-20T00:00:00.000Z","score":0.00567,"percentile":null},{"date":"2026-09-21T00:00:00.000Z","score":0.00567,"percentile":null},{"date":"2026-09-22T00:00:00.000Z","score":0.00567,"percentile":null},{"date":"2026-09-23T00:00:00.000Z","score":0.00567,"percentile":null},{"date":"2026-09-24T00:00:00.000Z","score":0.00725,"percentile":null},{"date":"2026-09-25T00:00:00.000Z","score":0.00725,"percentile":null},{"date":"2026-09-26T00:00:00.000Z","score":0.00725,"percentile":null},{"date":"2026-09-27T00:00:00.000Z","score":0.00725,"percentile":null},{"date":"2026-09-28T00:00:00.000Z","score":0.00725,"percentile":null},{"date":"2026-09-29T00:00:00.000Z","score":0.00725,"percentile":null},{"date":"2026-09-30T00:00:00.000Z","score":0.00725,"percentile":null},{"date":"2026-10-01T00:00:00.000Z","score":0.00725,"percentile":null},{"date":"2026-10-02T00:00:00.000Z","score":0.00725,"percentile":null},{"date":"2026-10-03T00:00:00.000Z","score":0.00725,"percentile":null},{"date":"2026-10-04T00:00:00.000Z","score":0.00725,"percentile":null},{"date":"2026-10-05T00:00:00.000Z","score":0.00725,"percentile":null},{"date":"2026-10-06T00:00:00.000Z","score":0.00725,"percentile":null},{"date":"2026-10-07T00:00:00.000Z","score":0.00725,"percentile":null},{"date":"2026-10-08T00:00:00.000Z","score":0.00725,"percentile":null},{"date":"2026-10-09T00:00:00.000Z","score":0.00725,"percentile":null},{"date":"2026-10-10T00:00:00.000Z","score":0.00725,"percentile":null},{"date":"2026-10-11T00:00:00.000Z","score":0.00725,"percentile":null},{"date":"2026-10-12T00:00:00.000Z","score":0.00725,"percentile":null},{"date":"2026-10-13T00:00:00.000Z","score":0.00725,"percentile":null},{"date":"2026-10-14T00:00:00.000Z","score":0.00725,"percentile":null},{"date":"2026-10-15T00:00:00.000Z","score":0.00725,"percentile":null},{"date":"2026-10-16T00:00:00.000Z","score":0.00725,"percentile":null},{"date":"2026-10-17T00:00:00.000Z","score":0.00725,"percentile":null},{"date":"2026-10-18T00:00:00.000Z","score":0.00725,"percentile":null},{"date":"2026-10-19T00:00:00.000Z","score":0.00725,"percentile":0.53252}]},"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-835","name":"Loop with Unreachable Exit Condition ('Infinite Loop')","description":"The product contains an iteration or loop with an exit condition that cannot be reached, i.e., an infinite loop.","type":"weakness","status":"Incomplete","abstraction":"Base","likelihoodOfExploit":null,"url":"https://cwe.mitre.org/data/definitions/835.html"},{"id":"CWE-400","name":"Uncontrolled Resource Consumption","description":"The product does not properly control the allocation and maintenance of a limited resource.","type":"weakness","status":"Draft","abstraction":"Class","likelihoodOfExploit":"High","url":"https://cwe.mitre.org/data/definitions/400.html"}],"affected":[{"vendor":"chainguard","product":"libssh","name":"libssh","label":"libssh","ecosystem":"Chainguard","cpePart":null,"purl":"pkg:apk/chainguard/libssh","purlType":"apk","versions":[{"text":"< 0.12.2-r0","noFixRecorded":false,"fixedIn":null}],"versionsText":"< 0.12.2-r0","eol":null,"hubHref":null},{"vendor":"chainguard","product":"libssh-dev","name":"libssh-dev","label":"libssh-dev","ecosystem":"Chainguard","cpePart":null,"purl":"pkg:apk/chainguard/libssh-dev","purlType":"apk","versions":[{"text":"< 0.12.2-r0","noFixRecorded":false,"fixedIn":null}],"versionsText":"< 0.12.2-r0","eol":null,"hubHref":null},{"vendor":"chainguard","product":"libssh2","name":"libssh2","label":"libssh2","ecosystem":"Chainguard","cpePart":null,"purl":"pkg:apk/chainguard/libssh2","purlType":"apk","versions":[{"text":"All versions","noFixRecorded":true,"fixedIn":null}],"versionsText":"All versions (No fix recorded)","eol":null,"hubHref":null},{"vendor":"wolfi","product":"libssh","name":"libssh","label":"libssh","ecosystem":"Wolfi","cpePart":null,"purl":"pkg:apk/wolfi/libssh","purlType":"apk","versions":[{"text":"< 0.12.2-r0","noFixRecorded":false,"fixedIn":null}],"versionsText":"< 0.12.2-r0","eol":null,"hubHref":null},{"vendor":"wolfi","product":"libssh-dev","name":"libssh-dev","label":"libssh-dev","ecosystem":"Wolfi","cpePart":null,"purl":"pkg:apk/wolfi/libssh-dev","purlType":"apk","versions":[{"text":"< 0.12.2-r0","noFixRecorded":false,"fixedIn":null}],"versionsText":"< 0.12.2-r0","eol":null,"hubHref":null},{"vendor":"wolfi","product":"libssh2","name":"libssh2","label":"libssh2","ecosystem":"Wolfi","cpePart":null,"purl":"pkg:apk/wolfi/libssh2","purlType":"apk","versions":[{"text":"All versions","noFixRecorded":true,"fixedIn":null}],"versionsText":"All versions (No fix recorded)","eol":null,"hubHref":null},{"vendor":"debian","product":"libssh","name":"libssh","label":"libssh","ecosystem":"Debian","cpePart":null,"purl":"pkg:deb/debian/libssh","purlType":"deb","versions":[{"text":"All versions","noFixRecorded":true,"fixedIn":null},{"text":"< 0.11.5-0+deb13u1","noFixRecorded":false,"fixedIn":null},{"text":"< 0.12.2-1","noFixRecorded":false,"fixedIn":null}],"versionsText":"All versions (No fix recorded) | < 0.11.5-0+deb13u1 | < 0.12.2-1","eol":null,"hubHref":null},{"vendor":"ubuntu","product":"libssh","name":"libssh","label":"libssh","ecosystem":"Ubuntu","cpePart":null,"purl":"pkg:deb/ubuntu/libssh","purlType":"deb","versions":[{"text":"All versions","noFixRecorded":true,"fixedIn":null},{"text":"< 0.9.6-2ubuntu0.22.04.8","noFixRecorded":false,"fixedIn":null},{"text":"< 0.10.6-2ubuntu0.5","noFixRecorded":false,"fixedIn":null},{"text":"< 0.11.3-1ubuntu2.1","noFixRecorded":false,"fixedIn":null}],"versionsText":"All versions (No fix recorded) | < 0.9.6-2ubuntu0.22.04.8 | < 0.10.6-2ubuntu0.5 | < 0.11.3-1ubuntu2.1","eol":null,"hubHref":null},{"vendor":"libssh","product":"libssh","name":"libssh","label":"libssh","ecosystem":null,"cpePart":"a","purl":null,"purlType":null,"versions":[{"text":"na","noFixRecorded":false,"fixedIn":null}],"versionsText":"na","eol":null,"hubHref":"/vendor/libssh/libssh"},{"vendor":"redhat","product":"enterprise_linux","name":"enterprise linux","label":"enterprise_linux","ecosystem":null,"cpePart":"o","purl":null,"purlType":null,"versions":[{"text":"8.0","noFixRecorded":false,"fixedIn":null},{"text":"9.0","noFixRecorded":false,"fixedIn":null},{"text":"10.0","noFixRecorded":false,"fixedIn":null}],"versionsText":"8.0 | 9.0 | 10.0","eol":{"isEol":false,"eolDate":"2029-05-31T00:00:00.000Z","matchMethod":"cpe","cycle":{"name":"8","label":"8 (Upcoming ELS)","eolFrom":"2029-05-31T00:00:00.000Z","isLts":false,"isMaintained":true,"latestVersion":"8.10"},"product":{"name":"rhel","label":"Red Hat Enterprise Linux","category":"os"}},"hubHref":"/vendor/redhat/enterprise_linux"},{"vendor":"redhat","product":"hardened_images","name":"hardened images","label":"hardened_images","ecosystem":null,"cpePart":"a","purl":null,"purlType":null,"versions":[{"text":"na","noFixRecorded":false,"fixedIn":null}],"versionsText":"na","eol":null,"hubHref":"/vendor/redhat/hardened_images"}],"affectedCount":11,"eol":{"hasEol":false,"count":0},"references":[{"url":"https://access.redhat.com/errata/RHSA-2026:42922","label":"access.redhat.com/errata/RHSA-2026:42922","hostname":"access.redhat.com","tags":["Vendor Advisory","X Refsource REDHAT"]},{"url":"https://access.redhat.com/errata/RHSA-2026:55855","label":"access.redhat.com/errata/RHSA-2026:55855","hostname":"access.redhat.com","tags":["Vendor Advisory","X Refsource REDHAT"]},{"url":"https://access.redhat.com/errata/RHSA-2026:62217","label":"access.redhat.com/errata/RHSA-2026:62217","hostname":"access.redhat.com","tags":["Vendor Advisory","X Refsource REDHAT"]},{"url":"https://access.redhat.com/errata/RHSA-2026:62218","label":"access.redhat.com/errata/RHSA-2026:62218","hostname":"access.redhat.com","tags":["Vendor Advisory","X Refsource REDHAT"]},{"url":"https://access.redhat.com/security/cve/CVE-2026-59843","label":"access.redhat.com/security/cve/CVE-2026-59843","hostname":"access.redhat.com","tags":["VDB Entry","X Refsource REDHAT","Vendor Advisory"]},{"url":"https://bugzilla.redhat.com/show_bug.cgi?id=2498176","label":"bugzilla.redhat.com/show_bug.cgi?id=2498176","hostname":"bugzilla.redhat.com","tags":["Issue Tracking","X Refsource REDHAT","Vendor Advisory"]},{"url":"https://ubuntu.com/security/CVE-2026-59843","label":"ubuntu.com/security/CVE-2026-59843","hostname":"ubuntu.com","tags":["REPORT"]},{"url":"https://www.cve.org/CVERecord?id=CVE-2026-59843","label":"www.cve.org/CVERecord?id=CVE-2026-59843","hostname":"www.cve.org","tags":["REPORT"]},{"url":"https://www.libssh.org/2026/07/21/libssh-0-12-1-and-0-11-5-security-releases/","label":"www.libssh.org/2026/07/21/libssh-0-12-1-and-0-11-5-security-releases/","hostname":"www.libssh.org","tags":["REPORT"]},{"url":"https://www.libssh.org/security/advisories/CVE-2026-59843.txt","label":"www.libssh.org/security/advisories/CVE-2026-59843.txt","hostname":"www.libssh.org","tags":["REPORT"]},{"url":"https://ubuntu.com/security/notices/USN-8699-1","label":"ubuntu.com/security/notices/USN-8699-1","hostname":"ubuntu.com","tags":["Advisory"]},{"url":"https://security-tracker.debian.org/tracker/CVE-2026-59843","label":"security-tracker.debian.org/tracker/CVE-2026-59843","hostname":"security-tracker.debian.org","tags":["Advisory"]},{"url":"https://nvd.nist.gov/vuln/detail/CVE-2026-59843","label":"nvd.nist.gov/vuln/detail/CVE-2026-59843","hostname":"nvd.nist.gov","tags":["Oval","Advisory"]}],"lineage":{"upstream":[],"downstream":["MGASA-2026-0425","OPENSUSE-SU-2026:11377-1","OPENSUSE-SU-2026:21444-1","RHSA-2026:42922","RHSA-2026:55855","RHSA-2026:62217","RHSA-2026:62218","SUSE-SU-2026:22940-1","SUSE-SU-2026:22948-1","SUSE-SU-2026:22956-1","SUSE-SU-2026:23056-1","SUSE-SU-2026:23168-1","SUSE-SU-2026:3302-1","SUSE-SU-2026:3330-1","SUSE-SU-2026:3463-1","USN-8699-1"],"duplicates":[],"related":["CGA-W8M5-5C9R-4R59","OPENSUSE-SU-2026:11377-1","OPENSUSE-SU-2026:21444-1","SUSE-SU-2026:22940-1","SUSE-SU-2026:22948-1","SUSE-SU-2026:22956-1","SUSE-SU-2026:23056-1","SUSE-SU-2026:23168-1","SUSE-SU-2026:3302-1","SUSE-SU-2026:3330-1","SUSE-SU-2026:3463-1","USN-8699-1"]},"timeline":[{"kind":"published","date":"2026-07-21T11:16:12.061Z","label":"Published","detail":"Vulnerability first disclosed.","source":null},{"kind":"modified","date":"2026-09-01T20:01:39.685Z","label":"Last modified","detail":"Vulnerability information updated.","source":null}],"risk":{"score":26,"level":"medium","profile":"Default","thresholds":{"critical":75,"high":50,"medium":25,"low":10}},"meta":{"dataAsOf":"2026-10-20T03:36:45.963Z","stale":false,"partial":false}}