{ "dataType": "CVE_RECORD", "dataVersion": "5.2", "cveMetadata": { "cveId": "CVE-2023-53867", "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "state": "PUBLISHED", "assignerShortName": "Linux", "dateReserved": "2025-12-09T01:27:17.829Z", "datePublished": "2025-12-24T10:55:25.430Z", "dateUpdated": "2026-08-05T09:16:28.667Z" }, "containers": { "cna": { "providerMetadata": { "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "shortName": "Linux", "dateUpdated": "2026-08-05T09:16:28.667Z" }, "descriptions": [ { "lang": "en", "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nceph: fix potential use-after-free bug when trimming caps\n\nWhen trimming the caps and just after the 'session->s_cap_lock' is\nreleased in ceph_iterate_session_caps() the cap maybe removed by\nanother thread, and when using the stale cap memory in the callbacks\nit will trigger use-after-free crash.\n\nWe need to check the existence of the cap just after the 'ci->i_ceph_lock'\nbeing acquired. And do nothing if it's already removed." } ], "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 - Every caller of the vulnerable `ceph_iterate_session_caps()` is driven by a message received from the remote Ceph MDS over TCP — `CEPH_SESSION_RECALL_STATE` (trim), `CLOSE`/`REJECT` (remove_session_caps), `STALE` (renewcaps) and MDS reconnect — processed in `handle_session()` on the messenger workqueue. A malicious, compromised, or on-path-spoofed MDS reaches the code purely with network traffic.\nAC:L - The attacker drives both sides of the race: `RECALL_STATE`/session-close/reconnect storms start the cap iteration while concurrent cap-revoke/export/session messages and the callback's own `d_prune_aliases()`/inode-eviction path remove caps. The window spans sleeping operations (`d_find_primary()`, `ceph_mdsc_build_path()`, dentry pruning) and can be retried indefinitely, so it is reliably hit.\nPR:N - No credentials or privileges on the victim client are required — the malicious MDS peer needs no local authority, and the code runs unauthenticated with respect to the client's privilege model. Locally, mere unprivileged access to a mounted CephFS is enough to generate the concurrent cap churn.\nUI:N - Exploitation needs no victim action beyond an already-mounted CephFS, which is the normal operating state of an affected system; the MDS drives the whole sequence on its own.\nS:U - The stale `struct ceph_cap` corruption and the resulting oops are confined to the kernel's own security authority; no VM, IOMMU, or sandbox boundary is crossed.\nC:H - The use-after-free gives a read primitive over freed/recycled `ceph_cap` slab memory, and `reconnect_caps_cb()` encodes those stale fields (`cap->cap_id`, `cap->issued`) directly into the reconnect message transmitted to the MDS, exfiltrating freed-object contents to the attacker.\nI:H - The callbacks write into the stale object — `cap->seq/issue_seq/mseq/cap_gen = 0` in `reconnect_caps_cb()` and `cap->issued = cap->implemented = CEPH_CAP_PIN` in `wake_up_session_cb()` — corrupting a recycled `ceph_cap` (and thus another inode's capability/coherency state), a UAF write primitive usable for heap grooming toward control-flow hijack.\nA:H - The reported real-world outcome is a kernel NULL-pointer dereference oops in `__ceph_remove_cap()` from the trim-caps path (Ceph tracker #43272), and any use-after-free of the cap object crashes the client; the MDS can trigger it repeatedly." } ] } ], "affected": [ { "product": "Linux", "vendor": "Linux", "defaultStatus": "unaffected", "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git", "programFiles": [ "fs/ceph/caps.c", "fs/ceph/debugfs.c", "fs/ceph/mds_client.c", "fs/ceph/mds_client.h", "fs/ceph/super.h" ], "versions": [ { "version": "2f2dc053404febedc9c273452d9d518fb31fde72", "lessThan": "2b2515b8095cf2149bef44383a99d5b5677f1831", "status": "affected", "versionType": "git" }, { "version": "2f2dc053404febedc9c273452d9d518fb31fde72", "lessThan": "448875a73e16ba7d81dec9274ce9d33a12d092fb", "status": "affected", "versionType": "git" }, { "version": "2f2dc053404febedc9c273452d9d518fb31fde72", "lessThan": "ae6e935618d99cdba11eab4714092e7e5f13cf7e", "status": "affected", "versionType": "git" }, { "version": "2f2dc053404febedc9c273452d9d518fb31fde72", "lessThan": "aaf67de78807c59c35bafb5003d4fb457c764800", "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/caps.c", "fs/ceph/debugfs.c", "fs/ceph/mds_client.c", "fs/ceph/mds_client.h", "fs/ceph/super.h" ], "versions": [ { "version": "2.6.34", "status": "affected" }, { "version": "0", "lessThan": "2.6.34", "status": "unaffected", "versionType": "semver" }, { "version": "6.1.28", "lessThanOrEqual": "6.1.*", "status": "unaffected", "versionType": "semver" }, { "version": "6.2.15", "lessThanOrEqual": "6.2.*", "status": "unaffected", "versionType": "semver" }, { "version": "6.3.2", "lessThanOrEqual": "6.3.*", "status": "unaffected", "versionType": "semver" }, { "version": "6.4", "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": "2.6.34", "versionEndExcluding": "6.1.28" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "2.6.34", "versionEndExcluding": "6.2.15" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "2.6.34", "versionEndExcluding": "6.3.2" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "2.6.34", "versionEndExcluding": "6.4" } ] } ] } ], "references": [ { "url": "https://git.kernel.org/stable/c/2b2515b8095cf2149bef44383a99d5b5677f1831" }, { "url": "https://git.kernel.org/stable/c/448875a73e16ba7d81dec9274ce9d33a12d092fb" }, { "url": "https://git.kernel.org/stable/c/ae6e935618d99cdba11eab4714092e7e5f13cf7e" }, { "url": "https://git.kernel.org/stable/c/aaf67de78807c59c35bafb5003d4fb457c764800" } ], "title": "ceph: fix potential use-after-free bug when trimming caps", "x_generator": { "engine": "bippy-1.2.0" } } } }