{"id":"CVE-2026-89650","title":"ceph: bound num_export_targets array for mds info v2/v3","summary":"In the Linux kernel, the following vulnerability has been resolved:\n\nceph: bound num_export_targets array for mds info v2/v3\n\nceph_mdsmap_decode() in fs/ceph/mdsmap.c reads num_export_targets from\neach per-mds info record and advances th…","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","cvssSource":"cna","cwe":["CWE-125"],"vendor":"Linux","product":"Linux","affected":["Linux >= d463a43d69f4af85887671d76182437775fd1631 < 0c4bcc3ba7291d383b82ce1c2fe324f69a42da2d","Linux >= d463a43d69f4af85887671d76182437775fd1631 < 55a06b32438c222765138727d0a8164b103e8f0d","Linux >= d463a43d69f4af85887671d76182437775fd1631 < eb3e1a1cb1634c76d59c5a9cb1a026fc69d40911","Linux >= d463a43d69f4af85887671d76182437775fd1631 < 3bf7dba8dba9a05774b846affec61a3624ddba38","Linux >= d463a43d69f4af85887671d76182437775fd1631 < 58c2d3e954c13694ef6e820a5e9456461bb9e7df","Linux >= d463a43d69f4af85887671d76182437775fd1631 < 332c444f4dc6fa1e8b8637c9e82d29e97f768656","Linux >= d463a43d69f4af85887671d76182437775fd1631 < a3eb169ee297aa99670ba927c659990bd1e453f3","Linux 4.7"],"ssvc":{"exploitation":"none","automatable":"yes","technicalImpact":"partial","timestamp":"2026-10-16T19:25:14.842752Z"},"published":"2026-09-11","updated":"2026-10-19","sourceUpdated":"2026-10-19T08:50:21.912Z","source":"CVEORG","sourceUrl":"https://www.cve.org/CVERecord?id=CVE-2026-89650","references":[{"url":"https://git.kernel.org/stable/c/0c4bcc3ba7291d383b82ce1c2fe324f69a42da2d"},{"url":"https://git.kernel.org/stable/c/55a06b32438c222765138727d0a8164b103e8f0d"},{"url":"https://git.kernel.org/stable/c/eb3e1a1cb1634c76d59c5a9cb1a026fc69d40911"},{"url":"https://git.kernel.org/stable/c/3bf7dba8dba9a05774b846affec61a3624ddba38"},{"url":"https://git.kernel.org/stable/c/58c2d3e954c13694ef6e820a5e9456461bb9e7df"},{"url":"https://git.kernel.org/stable/c/332c444f4dc6fa1e8b8637c9e82d29e97f768656"},{"url":"https://git.kernel.org/stable/c/a3eb169ee297aa99670ba927c659990bd1e453f3"},{"url":"https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-89650.json"},{"url":"https://access.redhat.com/security/cve/CVE-2026-89650"},{"url":"https://bugzilla.redhat.com/show_bug.cgi?id=2532105"},{"url":"https://www.cve.org/CVERecord?id=CVE-2026-89650"},{"url":"https://nvd.nist.gov/vuln/detail/CVE-2026-89650"},{"url":"https://git.kernel.org/pub/scm/linux/security/vulns.git/plain/cve/published/2026/CVE-2026-89650.mbox"}],"tags":["cve.org","csaf","vex","red-hat","score-dispute"],"epss":0.00502,"epssPercentile":0.42785,"scores":{"cna":9.1,"vendor":7},"ingestedAt":"2026-09-14T15:23:07.450Z","slug":"CVE-2026-89650","body":"## Overview\n\nIn the Linux kernel, the following vulnerability has been resolved:\n\nceph: bound num_export_targets array for mds info v2/v3\n\nceph_mdsmap_decode() in fs/ceph/mdsmap.c reads num_export_targets from\neach per-mds info record and advances the decode cursor by\nnum_export_targets * sizeof(u32) without first checking that many bytes\nremain. The only upper-bound check that catches a runaway cursor\n(*p > info_end) is gated on info_v >= 4, because info_end is left NULL\nfor info_v 2 and 3. When the monitor sends an MDS map whose per-mds\ninfo version is 2 or 3 with an oversized num_export_targets, the cursor\nmoves past the message front buffer and the later export-targets loop\ncalls the unchecked ceph_decode_32() on out-of-bounds memory.\n\nA kernel client processes CEPH_MSG_MDS_MAP from its monitor session\n(net/ceph/mon_client.c dispatches it; fs/ceph/super.c routes it to\nceph_mdsc_handle_mdsmap(), which sets end to the front buffer bound and\ncalls ceph_mdsmap_decode()). A malicious or compromised monitor, or an\non-path attacker on an unsigned/unencrypted messenger session, can\ntherefore drive an out-of-bounds read in the client kernel; on x86_64\nwith KASAN it is reported as a slab-out-of-bounds read in\nceph_mdsmap_decode(). The decoded values land in the internal\ninfo->export_targets[] array, so the consequence is a kernel\nout-of-bounds read, not an information leak to the attacker.\n\nImpact: a malicious or compromised Ceph monitor sending an MDS map with\na per-mds info version of 2 or 3 and an oversized num_export_targets\nfield triggers an out-of-bounds read in the CephFS client kernel.\n\nAdd a ceph_decode_need() for the export-targets array before advancing\nthe cursor, so the bound is enforced for every info_v >= 2, not only\ninfo_v >= 4. This mirrors the count-then-need idiom already used for\nm_data_pg_pools later in the same function.\n\nCompute the export-targets byte count with size_mul() and reuse that\nchecked length when advancing the cursor, so the attacker-controlled\nnum_export_targets multiplication fails closed on overflow rather than\nrelying on the later kcalloc() guard.\n\n## Affected\n\n- `Linux >= d463a43d69f4af85887671d76182437775fd1631 < 0c4bcc3ba7291d383b82ce1c2fe324f69a42da2d`\n- `Linux >= d463a43d69f4af85887671d76182437775fd1631 < 55a06b32438c222765138727d0a8164b103e8f0d`\n- `Linux >= d463a43d69f4af85887671d76182437775fd1631 < eb3e1a1cb1634c76d59c5a9cb1a026fc69d40911`\n- `Linux >= d463a43d69f4af85887671d76182437775fd1631 < 3bf7dba8dba9a05774b846affec61a3624ddba38`\n- `Linux >= d463a43d69f4af85887671d76182437775fd1631 < 58c2d3e954c13694ef6e820a5e9456461bb9e7df`\n- `Linux >= d463a43d69f4af85887671d76182437775fd1631 < 332c444f4dc6fa1e8b8637c9e82d29e97f768656`\n- `Linux >= d463a43d69f4af85887671d76182437775fd1631 < a3eb169ee297aa99670ba927c659990bd1e453f3`\n- `Linux 4.7`\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 7, Red Hat Enterprise Linux 8, Red Hat Enterprise Linux 9, Red Hat OpenShift Container Platform 4 · no fix planned: Red Hat Enterprise Linux 10, Red Hat Enterprise Linux 7, Red Hat Enterprise Linux 8, Red Hat Enterprise Linux 9, … · updated 2026-09-18 · [vex](https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-89650.json)","depth":"midnight","depthScore":50,"depthScoreParts":{"impact":50.1,"likelihood":0.1,"exploitation":0,"ransomware":0},"changes":[{"seq":223257,"id":"CVE-2026-89650","ts":1792180032970,"field":"cvss","old":"7","new":"9.1"},{"seq":223256,"id":"CVE-2026-89650","ts":1792180032970,"field":"severity","old":"high","new":"critical"},{"seq":208158,"id":"CVE-2026-89650","ts":1789922725472,"field":"cvss","old":"9.1","new":"7"},{"seq":208157,"id":"CVE-2026-89650","ts":1789922725472,"field":"severity","old":"critical","new":"high"},{"seq":197797,"id":"CVE-2026-89650","ts":1789384318898,"field":"cvss","old":"7.5","new":"9.1"},{"seq":197796,"id":"CVE-2026-89650","ts":1789384318898,"field":"severity","old":"high","new":"critical"},{"seq":183379,"id":"CVE-2026-89650","ts":1789356675118,"field":"cvss","old":"9.1","new":"7.5"},{"seq":183378,"id":"CVE-2026-89650","ts":1789356675118,"field":"severity","old":"critical","new":"high"},{"seq":153498,"id":"CVE-2026-89650","ts":1789285350806,"field":"cvss","old":null,"new":"9.1"},{"seq":153497,"id":"CVE-2026-89650","ts":1789285350806,"field":"severity","old":"none","new":"critical"},{"seq":147788,"id":"CVE-2026-89650","ts":1789270212292,"field":"cvss","old":null,"new":"7.5"},{"seq":147787,"id":"CVE-2026-89650","ts":1789270212292,"field":"severity","old":"none","new":"high"},{"seq":109544,"id":"CVE-2026-89650","ts":1789183732354,"field":"cvss","old":null,"new":"7.5"},{"seq":109543,"id":"CVE-2026-89650","ts":1789183732354,"field":"severity","old":"none","new":"high"}]}