{ "dataType": "CVE_RECORD", "dataVersion": "5.2", "cveMetadata": { "cveId": "CVE-2026-89990", "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "state": "PUBLISHED", "assignerShortName": "Linux", "dateReserved": "2026-09-11T19:38:34.780Z", "datePublished": "2026-09-16T10:33:04.371Z", "dateUpdated": "2026-10-19T08:56:04.591Z" }, "containers": { "cna": { "providerMetadata": { "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "shortName": "Linux", "dateUpdated": "2026-10-19T08:56:04.591Z" }, "descriptions": [ { "lang": "en", "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nceph: lock mutex in ceph_mds_check_access()\n\nMDS session OPEN handling replaces mdsc->s_cap_auths under\nmdsc->mutex, freeing the previous array and its strings.\n\nceph_mds_check_access() traverses this array without holding the\nmutex. A concurrent session reopen can therefore free the array while\nit is being inspected, resulting in a use-after-free like this:\n\n Unable to handle kernel paging request at virtual address 003aaad64b2c8bb9\n [...]\n Internal error: Oops: 0000000096000004 [#1] SMP\n Modules linked in:\n CPU: 56 UID: 2953037534 PID: 1253231 Comm: php-cgi8.4 Not tainted 6.18.45-i2-ampere #1146 NONE\n [..]\n pc : ceph_mds_check_access+0xd4/0x550\n lr : ceph_mds_check_access+0xc8/0x550\n [...]\n Call trace:\n ceph_mds_check_access+0xd4/0x550 (P)\n ceph_atomic_open+0x138/0xbe8\n path_openat+0xa24/0xfa8\n do_filp_open+0x94/0x158\n do_sys_openat2+0x88/0xf8" } ], "metrics": [ { "cvssV3_1": { "version": "3.1", "vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H", "baseScore": 9.8, "baseSeverity": "CRITICAL" }, "scenarios": [ { "lang": "en", "value": "AV:N - handle_session() frees mdsc->s_cap_auths on CEPH_SESSION_OPEN delivered over the Ceph messenger TCP session (mds_dispatch, CEPH_MSG_CLIENT_SESSION). CephFS re-exported via nfsd/ksmbd also lets a remote client reach the unlocked walker through ceph_atomic_open.\nAC:L - A malicious MDS may send CEPH_SESSION_OPEN even on an already-open session, freeing and replacing s_cap_auths under mdsc->mutex at will. Concurrent open/unlink/setattr, including nfsd/ksmbd on a CephFS export, walk that array without the mutex; the MDS can retry while those operations are in flight.\nPR:N - The attacker is the remote MDS peer, or an NFS/SMB client of a CephFS re-export, and needs no Linux UID, capability, or init-namespace root on the victim host, matching other MDS-driven CephFS client CVEs such as CVE-2026-89651.\nUI:N - Once CephFS is mounted, as is standard in Rook, Kubernetes, and OpenStack, SESSION_OPEN and VFS/nfsd opens run without any further interactive victim action such as mounting media or opening a user-supplied file at exploit time.\nS:U - The use-after-free corrupts kernel heap on the CephFS client host and remains in that kernel's security authority; it is not a VM escape, IOMMU bypass, or sandbox boundary crossing.\nC:H - ceph_mds_check_access() and ceph_mds_auth_match() dereference the freed s_cap_auths array and its match.path, gids, and fs_name strings; a use-after-free of those objects enables arbitrary kernel read via heap reuse and is High per kernel UAF guidance.\nI:H - The same UAF is heap-sprayable with attacker-controlled SESSION_OPEN allocations (cap_auths_num and string lengths), yielding write and control-flow primitives; kernel guidance scores use-after-free integrity as High.\nA:H - The reported oops is a kernel paging fault in ceph_mds_check_access from ceph_atomic_open on the freed array; repeating SESSION_OPEN while the walker runs can oops or panic the client, which is High availability impact." } ] } ], "affected": [ { "product": "Linux", "vendor": "Linux", "defaultStatus": "unaffected", "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git", "programFiles": [ "fs/ceph/mds_client.c", "fs/ceph/mds_client.h" ], "versions": [ { "version": "596afb0b8933ba6ed7227adcc538db26feb25c74", "lessThan": "729c1ff670ece6f3d4b1738365a0b2f90d487523", "status": "affected", "versionType": "git" }, { "version": "596afb0b8933ba6ed7227adcc538db26feb25c74", "lessThan": "ca5bfea2045ef2eb3305cf2a9d8da549b76c37d3", "status": "affected", "versionType": "git" }, { "version": "596afb0b8933ba6ed7227adcc538db26feb25c74", "lessThan": "df1a97d5313fccadb08390306d49b194fb027392", "status": "affected", "versionType": "git" }, { "version": "596afb0b8933ba6ed7227adcc538db26feb25c74", "lessThan": "a61c6ae1dae2611082b831b4aaa780878099c012", "status": "affected", "versionType": "git" } ] }, { "product": "Linux", "vendor": "Linux", "defaultStatus": "affected", "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git", "programFiles": [ "fs/ceph/mds_client.c", "fs/ceph/mds_client.h" ], "versions": [ { "version": "6.10", "status": "affected" }, { "version": "0", "lessThan": "6.10", "status": "unaffected", "versionType": "semver" }, { "version": "6.12.110", "lessThanOrEqual": "6.12.*", "status": "unaffected", "versionType": "semver" }, { "version": "6.18.51", "lessThanOrEqual": "6.18.*", "status": "unaffected", "versionType": "semver" }, { "version": "7.2.5", "lessThanOrEqual": "7.2.*", "status": "unaffected", "versionType": "semver" }, { "version": "7.3", "lessThanOrEqual": "*", "status": "unaffected", "versionType": "original_commit_for_fix" } ] } ], "cpeApplicability": [ { "nodes": [ { "operator": "OR", "negate": false, "cpeMatch": [ { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "6.10", "versionEndExcluding": "6.12.110" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "6.10", "versionEndExcluding": "6.18.51" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "6.10", "versionEndExcluding": "7.2.5" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "6.10", "versionEndExcluding": "7.3" } ] } ] } ], "references": [ { "url": "https://git.kernel.org/stable/c/729c1ff670ece6f3d4b1738365a0b2f90d487523" }, { "url": "https://git.kernel.org/stable/c/ca5bfea2045ef2eb3305cf2a9d8da549b76c37d3" }, { "url": "https://git.kernel.org/stable/c/df1a97d5313fccadb08390306d49b194fb027392" }, { "url": "https://git.kernel.org/stable/c/a61c6ae1dae2611082b831b4aaa780878099c012" } ], "title": "ceph: lock mutex in ceph_mds_check_access()", "x_generator": { "engine": "bippy-1.2.0" } } } }