{"id":"CVE-2026-89630","title":"In the Linux kernel, the following vulnerability has been resolved:\n\nsmb: client: restore the data_offset bound in is_valid_oplock_break()\n\nCommit 83bfbd0bb902 (\"cifs: Remove the RFC1002 header from smb_hdr\")\nchanged the quantity this bo…","summary":"In the Linux kernel, the following vulnerability has been resolved:\n\nsmb: client: restore the data_offset bound in is_valid_oplock_break()\n\nCommit 83bfbd0bb902 (\"cifs: Remove the RFC1002 header from smb_hdr\")\nchanged the quantity this bo…","severity":"critical","cvss":9.1,"cvssVector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:H","cwe":["CWE-125"],"vendor":"Red Hat","product":"Red Hat Enterprise Linux 9","affected":["enterprise_linux 10","enterprise_linux 9","openshift_container_platform 4"],"published":"2026-09-11","updated":"2026-10-11","sourceUpdated":"2026-10-11T14:17:07.743","source":"NVD","sourceUrl":"https://nvd.nist.gov/vuln/detail/CVE-2026-89630","references":[{"url":"https://git.kernel.org/stable/c/5b16a1967a01ad4496a7206a87c3eb16f1df2b05","label":"416baaa9-dc9f-4396-8d5f-8c081fb06d67"},{"url":"https://git.kernel.org/stable/c/ba22f575de9deeae4ae0859ca4315a7698226237","label":"416baaa9-dc9f-4396-8d5f-8c081fb06d67"},{"url":"https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-89630.json"},{"url":"https://access.redhat.com/security/cve/CVE-2026-89630"},{"url":"https://bugzilla.redhat.com/show_bug.cgi?id=2532051"},{"url":"https://www.cve.org/CVERecord?id=CVE-2026-89630"},{"url":"https://nvd.nist.gov/vuln/detail/CVE-2026-89630"},{"url":"https://git.kernel.org/pub/scm/linux/security/vulns.git/plain/cve/published/2026/CVE-2026-89630.mbox"}],"tags":["nvd","csaf","vex","red-hat","cve.org","score-dispute"],"epss":0.00539,"epssPercentile":0.4515,"scores":{"nvd":9.1,"vendor":7,"cna":9.1},"ingestedAt":"2026-09-14T15:23:07.474Z","slug":"CVE-2026-89630","body":"## Overview\n\nIn the Linux kernel, the following vulnerability has been resolved:\n\nsmb: client: restore the data_offset bound in is_valid_oplock_break()\n\nCommit 83bfbd0bb902 (\"cifs: Remove the RFC1002 header from smb_hdr\")\nchanged the quantity this bound is measured against.  It used to be\nsrv->total_read minus the 4-byte RFC1002 preamble that total_read then\nincluded, so it was the SMB message length.  The same commit stopped\ncounting the preamble, and the mechanical substitution to\nsrv->total_read - srv->pdu_size left an expression that is identically\nzero: standard_receive3() reads MID_HEADER_SIZE() bytes and then exactly\npdu_length - MID_HEADER_SIZE() more, adding both to total_read.\n\nlen is therefore 0, the subtraction below it wraps, and no __u32\nDataOffset can exceed the result, so the check from commit 097f5863b1a0\n(\"cifs: read overflow in is_valid_oplock_break()\") no longer rejects\nanything.  Use total_read, which is now the message length on its own.\n\n## Remediation\n\nRefer to the linked advisories for vendor-supplied fixes and affected version ranges.\n\n## Vendor advisories\n\n- **Red Hat VEX** · Moderate · affected: Red Hat Enterprise Linux 10, Red Hat Enterprise Linux 9, Red Hat OpenShift Container Platform 4 · no fix planned: Red Hat Enterprise Linux 10, Red Hat Enterprise Linux 9, Red Hat OpenShift Container Platform 4 · updated 2026-09-14 · [vex](https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-89630.json)","depth":"midnight","depthScore":50,"depthScoreParts":{"impact":50.1,"likelihood":0.1,"exploitation":0,"ransomware":0},"changes":[{"seq":219421,"id":"CVE-2026-89630","ts":1791816804959,"field":"cvss","old":"7","new":"9.1"},{"seq":219420,"id":"CVE-2026-89630","ts":1791816804959,"field":"severity","old":"high","new":"critical"},{"seq":204223,"id":"CVE-2026-89630","ts":1789490240332,"field":"cvss","old":"6.3","new":"7"},{"seq":204222,"id":"CVE-2026-89630","ts":1789490240332,"field":"severity","old":"medium","new":"high"},{"seq":202851,"id":"CVE-2026-89630","ts":1789403732668,"field":"cvss","old":"9.1","new":"6.3"},{"seq":202850,"id":"CVE-2026-89630","ts":1789403732668,"field":"severity","old":"critical","new":"medium"},{"seq":197840,"id":"CVE-2026-89630","ts":1789384320619,"field":"cvss","old":"6.3","new":"9.1"},{"seq":197839,"id":"CVE-2026-89630","ts":1789384320619,"field":"severity","old":"medium","new":"critical"},{"seq":183391,"id":"CVE-2026-89630","ts":1789356675168,"field":"cvss","old":"9.1","new":"6.3"},{"seq":183390,"id":"CVE-2026-89630","ts":1789356675168,"field":"severity","old":"critical","new":"medium"},{"seq":153464,"id":"CVE-2026-89630","ts":1789285350615,"field":"cvss","old":null,"new":"9.1"},{"seq":153463,"id":"CVE-2026-89630","ts":1789285350615,"field":"severity","old":"none","new":"critical"},{"seq":147790,"id":"CVE-2026-89630","ts":1789270212300,"field":"cvss","old":null,"new":"6.3"},{"seq":147789,"id":"CVE-2026-89630","ts":1789270212300,"field":"severity","old":"none","new":"medium"},{"seq":109546,"id":"CVE-2026-89630","ts":1789183732362,"field":"cvss","old":null,"new":"6.3"},{"seq":109545,"id":"CVE-2026-89630","ts":1789183732362,"field":"severity","old":"none","new":"medium"}]}