{"api_version":"1","generated_at":"2026-10-15T23:43:48+00:00","cve":"CVE-2023-54107","urls":{"html":"https://cve.report/CVE-2023-54107","api":"https://cve.report/api/cve/CVE-2023-54107.json","docs":"https://cve.report/api","cve_org":"https://www.cve.org/CVERecord?id=CVE-2023-54107","nvd":"https://nvd.nist.gov/vuln/detail/CVE-2023-54107"},"summary":{"title":"blk-cgroup: dropping parent refcount after pd_free_fn() is done","description":"In the Linux kernel, the following vulnerability has been resolved:\n\nblk-cgroup: dropping parent refcount after pd_free_fn() is done\n\nSome cgroup policies will access parent pd through child pd even\nafter pd_offline_fn() is done. If pd_free_fn() for parent is called\nbefore child, then UAF can be triggered. Hence it's better to guarantee\nthe order of pd_free_fn().\n\nCurrently refcount of parent blkg is dropped in __blkg_release(), which\nis before pd_free_fn() is called in blkg_free_work_fn() while\nblkg_free_work_fn() is called asynchronously.\n\nThis patch make sure pd_free_fn() called from removing cgroup is ordered\nby delaying dropping parent refcount after calling pd_free_fn() for\nchild.\n\nBTW, pd_free_fn() will also be called from blkcg_deactivate_policy()\nfrom deleting device, and following patches will guarantee the order.","state":"PUBLISHED","assigner":"Linux","published_at":"2025-12-24 13:16:12","updated_at":"2026-10-15 22:17:53"},"problem_types":[],"metrics":[{"version":"3.1","source":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","type":"Secondary","score":"7.8","severity":"HIGH","vector":"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H","data":{"version":"3.1","vectorString":"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H","baseScore":7.8,"baseSeverity":"HIGH","attackVector":"LOCAL","attackComplexity":"LOW","privilegesRequired":"LOW","userInteraction":"NONE","scope":"UNCHANGED","confidentialityImpact":"HIGH","integrityImpact":"HIGH","availabilityImpact":"HIGH"}},{"version":"3.1","source":"CNA","type":"DECLARED","score":"7.8","severity":"HIGH","vector":"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H","data":{"baseScore":7.8,"baseSeverity":"HIGH","vectorString":"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H","version":"3.1"}}],"references":[{"url":"https://git.kernel.org/stable/c/c7241babf0855d8a6180cd1743ff0ec34de40b4e","name":"https://git.kernel.org/stable/c/c7241babf0855d8a6180cd1743ff0ec34de40b4e","refsource":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","tags":[],"title":"","mime":"","httpstatus":"","archivestatus":"0"},{"url":"https://www.cve.org/CVERecord?id=CVE-2023-54107","name":"CVE Program record","refsource":"CVE.ORG","tags":["canonical"]},{"url":"https://nvd.nist.gov/vuln/detail/CVE-2023-54107","name":"NVD vulnerability detail","refsource":"NVD","tags":["canonical","analysis"]}],"affected":[{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected d578c770c85233af592e54537f93f3831bde7e9a c7241babf0855d8a6180cd1743ff0ec34de40b4e git","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected 5.18","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"unaffected 5.18 semver","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"unaffected 6.3 * original_commit_for_fix","platforms":[]}],"timeline":[],"solutions":[],"workarounds":[],"exploits":[],"credits":[],"nvd_cpes":[],"vendor_comments":[],"enrichments":{"kev":null,"epss":{"cve_year":"2023","cve_id":"54107","cve":"CVE-2023-54107","epss":"0.001320000","percentile":"0.031310000","score_date":"2026-08-06","updated_at":"2026-08-07 00:14:20"},"legacy_qids":[]},"source_records":{"cve_program":{"containers":{"adp":[{"metrics":[{"other":{"content":{"id":"CVE-2023-54107","options":[{"Exploitation":"none"},{"Automatable":"no"},{"Technical Impact":"total"}],"role":"CISA Coordinator","timestamp":"2026-10-15T21:38:32.237187Z","version":"2.0.3"},"type":"ssvc"}}],"providerMetadata":{"dateUpdated":"2026-10-15T21:41:39.921Z","orgId":"134c704f-9b21-4f2e-91b3-4a467353bcc0","shortName":"CISA-ADP"},"title":"CISA ADP Vulnrichment"}],"cna":{"affected":[{"defaultStatus":"unaffected","product":"Linux","programFiles":["block/blk-cgroup.c"],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","vendor":"Linux","versions":[{"lessThan":"c7241babf0855d8a6180cd1743ff0ec34de40b4e","status":"affected","version":"d578c770c85233af592e54537f93f3831bde7e9a","versionType":"git"}]},{"defaultStatus":"affected","product":"Linux","programFiles":["block/blk-cgroup.c"],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","vendor":"Linux","versions":[{"status":"affected","version":"5.18"},{"lessThan":"5.18","status":"unaffected","version":"0","versionType":"semver"},{"lessThanOrEqual":"*","status":"unaffected","version":"6.3","versionType":"original_commit_for_fix"}]}],"cpeApplicability":[{"nodes":[{"cpeMatch":[{"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionEndExcluding":"6.3","versionStartIncluding":"5.18","vulnerable":true}],"negate":false,"operator":"OR"}]}],"descriptions":[{"lang":"en","value":"In the Linux kernel, the following vulnerability has been resolved:\n\nblk-cgroup: dropping parent refcount after pd_free_fn() is done\n\nSome cgroup policies will access parent pd through child pd even\nafter pd_offline_fn() is done. If pd_free_fn() for parent is called\nbefore child, then UAF can be triggered. Hence it's better to guarantee\nthe order of pd_free_fn().\n\nCurrently refcount of parent blkg is dropped in __blkg_release(), which\nis before pd_free_fn() is called in blkg_free_work_fn() while\nblkg_free_work_fn() is called asynchronously.\n\nThis patch make sure pd_free_fn() called from removing cgroup is ordered\nby delaying dropping parent refcount after calling pd_free_fn() for\nchild.\n\nBTW, pd_free_fn() will also be called from blkcg_deactivate_policy()\nfrom deleting device, and following patches will guarantee the order."}],"metrics":[{"cvssV3_1":{"baseScore":7.8,"baseSeverity":"HIGH","vectorString":"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H","version":"3.1"},"scenarios":[{"lang":"en","value":"AV:L - Triggering requires local cgroup filesystem operations (mkdir/rmdir of nested cgroups, writes to io.max/io.weight/io.latency) plus block I/O to populate blkgs. There is no remote or adjacent-network path into blk-cgroup teardown.\nAC:L - Although the UAF arises from unordered asynchronous work items and timers, the attacker controls both sides — building the nested blkcg hierarchy, choosing the tear-down order and timing, looping thousands of create/destroy cycles, and loading system_wq to widen the window while pd_free_fn sleeps (hrtimer_cancel, blk_put_queue). The iocost/throttle timers also fire on their own, so the window recurs without any condition outside attacker influence.\nPR:L - An unprivileged local account with a delegated cgroup v2 subtree suffices — standard systemd user slices and rootless/OCI containers grant mkdir/rmdir plus ownership of the non-root io.max, io.weight and io.latency files in cgroups the user creates, and bfq/blk-throttle policies are active without any privileged setup. No real root in the initial namespace is needed.\nUI:N - The attacker performs the entire sequence — cgroup creation, I/O generation, and rmdir — in its own process with no action by any other user.\nS:U - The corruption is confined to kernel heap objects managed by the same kernel security authority; no VM, hypervisor, or IOMMU boundary is crossed.\nC:H - The freed parent ioc_gq/throtl_grp/bfq_group lives in a general kmalloc cache, and __propagate_weights()/current_hweight() read child_active_sum, child_inuse_sum, active and inuse straight out of the reclaimed slot, with results observable via io.stat and scheduling behaviour. Heap grooming turns this into a controllable kernel-memory disclosure primitive.\nI:H - __propagate_weights() performs read-modify-write arithmetic directly on the freed parent object (parent->child_active_sum += ..., parent->child_inuse_sum += ...) with deltas derived from attacker-chosen io.weight values, and throtl_rb_erase() writes rb-tree pointers into the freed parent service queue. Sprayed into an attacker-chosen reclaimed object, this is a write primitive leading to control-flow hijack and privilege escalation.\nA:H - Use-after-free access and modification of freed slab memory reliably produces KASAN splats, rb-tree/slab corruption, and kernel oops or panic, and the sequence can be repeated at will to crash the machine."}]}],"providerMetadata":{"dateUpdated":"2026-08-05T09:17:19.939Z","orgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","shortName":"Linux"},"references":[{"url":"https://git.kernel.org/stable/c/c7241babf0855d8a6180cd1743ff0ec34de40b4e"}],"title":"blk-cgroup: dropping parent refcount after pd_free_fn() is done","x_generator":{"engine":"bippy-1.2.0"}}},"cveMetadata":{"assignerOrgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","assignerShortName":"Linux","cveId":"CVE-2023-54107","datePublished":"2025-12-24T13:06:31.505Z","dateReserved":"2025-12-24T13:02:52.517Z","dateUpdated":"2026-10-15T21:41:39.921Z","state":"PUBLISHED"},"dataType":"CVE_RECORD","dataVersion":"5.2"},"nvd":{"publishedDate":"2025-12-24 13:16:12","lastModifiedDate":"2026-10-15 22:17:53","problem_types":[],"metrics":{"cvssMetricV31":[{"source":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","type":"Secondary","cvssData":{"version":"3.1","vectorString":"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H","baseScore":7.8,"baseSeverity":"HIGH","attackVector":"LOCAL","attackComplexity":"LOW","privilegesRequired":"LOW","userInteraction":"NONE","scope":"UNCHANGED","confidentialityImpact":"HIGH","integrityImpact":"HIGH","availabilityImpact":"HIGH"},"exploitabilityScore":1.8,"impactScore":5.9}],"ssvcV203":[{"source":"134c704f-9b21-4f2e-91b3-4a467353bcc0","ssvcData":{"timestamp":"2026-10-15T21:38:32.237187Z","id":"CVE-2023-54107","options":[{"exploitation":"none"},{"automatable":"no"},{"technicalImpact":"total"}],"role":"CISA Coordinator","version":"2.0.3"}}]},"configurations":[]},"legacy_mitre":{"record":{"CveYear":"2023","CveId":"54107","Ordinal":"1","Title":"blk-cgroup: dropping parent refcount after pd_free_fn() is done","CVE":"CVE-2023-54107","Year":"2023"},"notes":[{"CveYear":"2023","CveId":"54107","Ordinal":"1","NoteData":"In the Linux kernel, the following vulnerability has been resolved:\n\nblk-cgroup: dropping parent refcount after pd_free_fn() is done\n\nSome cgroup policies will access parent pd through child pd even\nafter pd_offline_fn() is done. If pd_free_fn() for parent is called\nbefore child, then UAF can be triggered. Hence it's better to guarantee\nthe order of pd_free_fn().\n\nCurrently refcount of parent blkg is dropped in __blkg_release(), which\nis before pd_free_fn() is called in blkg_free_work_fn() while\nblkg_free_work_fn() is called asynchronously.\n\nThis patch make sure pd_free_fn() called from removing cgroup is ordered\nby delaying dropping parent refcount after calling pd_free_fn() for\nchild.\n\nBTW, pd_free_fn() will also be called from blkcg_deactivate_policy()\nfrom deleting device, and following patches will guarantee the order.","Type":"Description","Title":"blk-cgroup: dropping parent refcount after pd_free_fn() is done"}]}}}