{"id":"CVE-2026-59843","title":"Libssh: libssh: denial of service via zero advertised channel packet size","summary":"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.","severity":"medium","cvss":6.5,"cvssVector":"CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H","cvssSource":"cna","cwe":["CWE-835"],"vendor":"Red Hat","product":"libssh","affected":["libssh (all versions)","libssh (all versions)","libssh (all versions)","libssh (all versions)","libssh (all versions)","libssh-main (all versions)"],"ssvc":{"exploitation":"none","automatable":"no","technicalImpact":"partial","timestamp":"2026-07-21T12:08:16.810909Z"},"published":"2026-07-21","updated":"2026-11-05","sourceUpdated":"2026-11-05T22:18:33.616Z","source":"CVEORG","sourceUrl":"https://www.cve.org/CVERecord?id=CVE-2026-59843","references":[{"url":"https://access.redhat.com/errata/RHSA-2026:42922","label":"RHSA-2026:42922"},{"url":"https://access.redhat.com/errata/RHSA-2026:55855","label":"RHSA-2026:55855"},{"url":"https://access.redhat.com/errata/RHSA-2026:62217","label":"RHSA-2026:62217"},{"url":"https://access.redhat.com/errata/RHSA-2026:62218","label":"RHSA-2026:62218"},{"url":"https://access.redhat.com/security/cve/CVE-2026-59843"},{"url":"https://bugzilla.redhat.com/show_bug.cgi?id=2498176","label":"RHBZ#2498176"}],"tags":["cve.org"],"epss":0.00567,"epssPercentile":0.47253,"ingestedAt":"2026-11-05T23:41:31.948Z","slug":"CVE-2026-59843","body":"## Overview\n\nA 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.\n\n## Affected\n\n- `libssh (all versions)`\n- `libssh (all versions)`\n- `libssh (all versions)`\n- `libssh (all versions)`\n- `libssh (all versions)`\n- `libssh-main (all versions)`\n\n## Remediation\n\nRefer to the linked advisories for vendor-supplied fixes and affected version ranges.\n\n### Workarounds\n\nNo workaround available.","depth":"sunlit","depthScore":36,"depthScoreParts":{"impact":35.8,"likelihood":0.1,"exploitation":0,"ransomware":0},"changes":[]}