{"id":"CVE-2026-66808","title":"Microsoft SharePoint Server Remote Code Execution Vulnerability","summary":"Deserialization of untrusted data in Microsoft Office SharePoint allows an authorized attacker to execute code over a network.","severity":"high","cvss":8.8,"cvssVector":"CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H/E:U/RL:O/RC:C","cvssSource":"cna","cwe":["CWE-502","CWE-88"],"vendor":"Microsoft","product":"Microsoft SharePoint Enterprise Server 2016","affected":["sharepoint_enterprise_server_2016 >= 16.0.0 < 16.0.5565.1001","sharepoint_server_2019 >= 16.0.0 < 16.0.10417.20198","sharepoint_server_subscription_edition >= 16.0.0 < 16.0.19725.20522"],"ssvc":{"exploitation":"none","automatable":"no","technicalImpact":"total","timestamp":"2026-08-07T00:00:00+00:00"},"published":"2026-08-11","updated":"2026-10-21","sourceUpdated":"2026-10-21T20:54:42.353Z","source":"CVEORG","sourceUrl":"https://www.cve.org/CVERecord?id=CVE-2026-66808","references":[{"url":"https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-66808","label":"Microsoft SharePoint Server Remote Code Execution Vulnerability"},{"url":"https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-66808.json"},{"url":"https://access.redhat.com/security/cve/CVE-2026-66808"},{"url":"https://bugzilla.redhat.com/show_bug.cgi?id=2509774"},{"url":"https://www.cve.org/CVERecord?id=CVE-2026-66808"},{"url":"https://nvd.nist.gov/vuln/detail/CVE-2026-66808"},{"url":"https://github.com/stolostron/hypershift-addon-operator/pull/766"},{"url":"https://access.redhat.com/errata/RHSA-2026:54432"},{"url":"https://access.redhat.com/errata/RHSA-2026:57194"},{"url":"https://access.redhat.com/errata/RHSA-2026:59593"},{"url":"https://access.redhat.com/errata/RHSA-2026:59579"},{"url":"https://access.redhat.com/errata/RHSA-2026:59558"},{"url":"https://access.redhat.com/errata/RHSA-2026:59559"}],"tags":["cve.org","csaf","vex","red-hat"],"epss":0.02044,"epssPercentile":0.81074,"patched":["multicluster_engine_for_kubernetes 2.10","multicluster_engine_for_kubernetes 2.11","multicluster_engine_for_kubernetes 2.17","multicluster_engine_for_kubernetes 2.6","multicluster_engine_for_kubernetes 2.8","multicluster_engine_for_kubernetes 2.9"],"scores":{"cna":8.8,"vendor":8.7},"ingestedAt":"2026-09-08T18:07:34.888Z","slug":"CVE-2026-66808","body":"## Overview\n\nDeserialization of untrusted data in Microsoft Office SharePoint allows an authorized attacker to execute code over a network.\n\n## Affected\n\n- `sharepoint_enterprise_server_2016 >= 16.0.0 < 16.0.5565.1001`\n- `sharepoint_server_2019 >= 16.0.0 < 16.0.10417.20198`\n- `sharepoint_server_subscription_edition >= 16.0.0 < 16.0.19725.20522`\n\n## Remediation\n\nRefer to the linked advisories for vendor-supplied fixes and affected version ranges.\n\n## Vendor advisories\n\n- **RHSA-2026:54432** · Red Hat · fixed in: multicluster engine for Kubernetes 2.10 · released 2026-08-12 · [advisory](https://access.redhat.com/errata/RHSA-2026:54432)\n- **RHSA-2026:57194** · Red Hat · fixed in: multicluster engine for Kubernetes 2.11 · released 2026-08-19 · [advisory](https://access.redhat.com/errata/RHSA-2026:57194)\n- **RHSA-2026:59593** · Red Hat · fixed in: multicluster engine for Kubernetes 2.17 · released 2026-08-25 · [advisory](https://access.redhat.com/errata/RHSA-2026:59593)\n- **RHSA-2026:59579** · Red Hat · fixed in: multicluster engine for Kubernetes 2.6 · released 2026-08-25 · [advisory](https://access.redhat.com/errata/RHSA-2026:59579)\n- **RHSA-2026:59558** · Red Hat · fixed in: multicluster engine for Kubernetes 2.8 · released 2026-08-25 · [advisory](https://access.redhat.com/errata/RHSA-2026:59558)\n- **RHSA-2026:59559** · Red Hat · fixed in: multicluster engine for Kubernetes 2.9 · released 2026-08-25 · [advisory](https://access.redhat.com/errata/RHSA-2026:59559)","depth":"twilight","depthScore":49,"depthScoreParts":{"impact":48.4,"likelihood":0.4,"exploitation":0,"ransomware":0},"changes":[{"seq":211169,"id":"CVE-2026-66808","ts":1790367529418,"field":"cvss","old":"8.7","new":"8.8"},{"seq":210685,"id":"CVE-2026-66808","ts":1790322191876,"field":"cvss","old":"8.8","new":"8.7"}]}