{"id":"CVE-2026-89493","title":"kernel: ocfs2: validate rl_used against rl_count in refcount block validator (CVE-2026-89493)","summary":"A flaw was found in the Linux kernel's ocfs2 component. A local attacker with CAP_SYS_ADMIN privileges could exploit this by mounting a crafted or corrupted ocfs2 image, or by performing a raw write to the block device backing an already-m…","severity":"medium","cvss":5.5,"cvssVector":"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H","cvssSource":"vendor","cwe":"CWE-787","vendor":"Red Hat","product":"Linux","affected":["Linux >= f2c870e3b12e38da6d9b5b17c4c8ae56a0ed68e4 < f882e9e32d017a6569b2996c63ba3864717788e6","Linux >= f2c870e3b12e38da6d9b5b17c4c8ae56a0ed68e4 < 5593b63028cb43a6cda75a65ce1db95f00ea6857","Linux >= f2c870e3b12e38da6d9b5b17c4c8ae56a0ed68e4 < c8b02f4ee91e757b3fff556c7168b24b7ae55132","Linux >= f2c870e3b12e38da6d9b5b17c4c8ae56a0ed68e4 < 97584e93fc49a2d59252ac60467e9279f11b1b5b","Linux >= f2c870e3b12e38da6d9b5b17c4c8ae56a0ed68e4 < af56e90cb546cb0c47bef059335365283f61d6a4","Linux >= f2c870e3b12e38da6d9b5b17c4c8ae56a0ed68e4 < 0761d2c9494424469a0d30a9da3496ca010b0b2d","Linux >= f2c870e3b12e38da6d9b5b17c4c8ae56a0ed68e4 < 04ead708e13ddcb9c39319cbe02a18cef99cb823","Linux >= f2c870e3b12e38da6d9b5b17c4c8ae56a0ed68e4 < 4ca62df6bc0708947b48da3f6a712ecb8e73929c","Linux 2.6.32"],"published":"2026-09-11","updated":"2026-09-18","sourceUpdated":"2026-09-18T11:28:50+00:00","source":"CSAF","sourceUrl":"https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-89493.json","references":[{"url":"https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-89493.json"},{"url":"https://access.redhat.com/security/cve/CVE-2026-89493"},{"url":"https://bugzilla.redhat.com/show_bug.cgi?id=2532390"},{"url":"https://www.cve.org/CVERecord?id=CVE-2026-89493"},{"url":"https://nvd.nist.gov/vuln/detail/CVE-2026-89493"},{"url":"https://git.kernel.org/pub/scm/linux/security/vulns.git/plain/cve/published/2026/CVE-2026-89493.mbox"},{"url":"https://git.kernel.org/stable/c/f882e9e32d017a6569b2996c63ba3864717788e6"},{"url":"https://git.kernel.org/stable/c/5593b63028cb43a6cda75a65ce1db95f00ea6857"},{"url":"https://git.kernel.org/stable/c/c8b02f4ee91e757b3fff556c7168b24b7ae55132"},{"url":"https://git.kernel.org/stable/c/97584e93fc49a2d59252ac60467e9279f11b1b5b"},{"url":"https://git.kernel.org/stable/c/af56e90cb546cb0c47bef059335365283f61d6a4"},{"url":"https://git.kernel.org/stable/c/0761d2c9494424469a0d30a9da3496ca010b0b2d"},{"url":"https://git.kernel.org/stable/c/04ead708e13ddcb9c39319cbe02a18cef99cb823"},{"url":"https://git.kernel.org/stable/c/4ca62df6bc0708947b48da3f6a712ecb8e73929c"}],"tags":["csaf","vex","red-hat","cve.org","score-dispute"],"epss":0.00632,"epssPercentile":0.48966,"scores":{"vendor":5.5,"cna":8.8},"ingestedAt":"2026-09-14T15:23:07.452Z","slug":"CVE-2026-89493","body":"## Overview\n\nA flaw was found in the Linux kernel's ocfs2 component. A local attacker with CAP_SYS_ADMIN privileges could exploit this by mounting a crafted or corrupted ocfs2 image, or by performing a raw write to the block device backing an already-mounted ocfs2 filesystem. This vulnerability arises from insufficient validation of rl_used against rl_count in the refcount block validator, allowing an out-of-bounds read and write operation. Successful exploitation could lead to memory corruption and system instability.\n\n## Vendor advisories\n\n- **Red Hat VEX** · Moderate · updated 2026-09-18 · [vex](https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-89493.json)\n\n**kernel: ocfs2: validate rl_used against rl_count in refcount block validator** — rated Moderate by Red Hat. Released 2026-09-11, updated 2026-09-18.\n\nNot affected:\n\n- Red Hat Enterprise Linux 10\n- Red Hat Enterprise Linux 6\n- Red Hat Enterprise Linux 7\n- Red Hat Enterprise Linux 8\n- Red Hat Enterprise Linux 9\n- Red Hat OpenShift Container Platform 4\n\n## Remediation\n\nRefer to the advisory for fix availability.","depth":"sunlit","depthScore":30,"depthScoreParts":{"impact":30.3,"likelihood":0.1,"exploitation":0,"ransomware":0},"changes":[{"seq":206950,"id":"CVE-2026-89493","ts":1789749714142,"field":"cvss","old":"8.8","new":"5.5"},{"seq":206949,"id":"CVE-2026-89493","ts":1789749714142,"field":"severity","old":"high","new":"medium"},{"seq":198022,"id":"CVE-2026-89493","ts":1789384321421,"field":"cvss","old":"5.7","new":"8.8"},{"seq":198021,"id":"CVE-2026-89493","ts":1789384321421,"field":"severity","old":"medium","new":"high"},{"seq":183514,"id":"CVE-2026-89493","ts":1789356675679,"field":"cvss","old":"8.8","new":"5.7"},{"seq":183513,"id":"CVE-2026-89493","ts":1789356675679,"field":"severity","old":"high","new":"medium"},{"seq":153280,"id":"CVE-2026-89493","ts":1789285349864,"field":"cvss","old":null,"new":"8.8"},{"seq":153279,"id":"CVE-2026-89493","ts":1789285349864,"field":"severity","old":"none","new":"high"},{"seq":147281,"id":"CVE-2026-89493","ts":1789270206711,"field":"cvss","old":null,"new":"5.7"},{"seq":147280,"id":"CVE-2026-89493","ts":1789270206711,"field":"severity","old":"none","new":"medium"},{"seq":109034,"id":"CVE-2026-89493","ts":1789183730044,"field":"cvss","old":null,"new":"5.7"},{"seq":109033,"id":"CVE-2026-89493","ts":1789183730044,"field":"severity","old":"none","new":"medium"}]}