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Reference page — cumulative record through Monday, October 19, 2026 UTC. Reference pages update as the archive grows; only dated daily editions are immutable pages of record.

CVE-2024-56672

Linux Linux — blk-cgroup: Fix UAF in blkcg_unpin_online()
  AV  AC  PR  UI  S  C  I  A   CVSS    EPSS   %ile   KEV
   L   H   L   N  U  H  H  H    7.0   .0027   18.3     —
AFFECTED
  Product  Versions                                    Fixed
  Linux    4308a434e5e08c78676aa66bc626ef78cbef0883 –  —
  Linux    5.7 –                                       5.10.234
TIMELINE
  Dec 27  Reserved by Linux
  Dec 27  Published (CNA: Linux)
  Oct 15  RESCORED — CVE-2024-56672 (Linux). CVSS 7.8 → 7 (NVD).
CWE-416 · CNA: Linux · CVSS v3.1 · 9 references · NVD status: Modified

Description

In the Linux kernel, the following vulnerability has been resolved: blk-cgroup: Fix UAF in blkcg_unpin_online() blkcg_unpin_online() walks up the blkcg hierarchy putting the online pin. To walk up, it uses blkcg_parent(blkcg) but it was calling that after blkcg_destroy_blkgs(blkcg) which could free the blkcg, leading to the following UAF: ================================================================== BUG: KASAN: slab-use-after-free in blkcg_unpin_online+0x15a/0x270 Read of size 8 at addr ffff8881057678c0 by task kworker/9:1/117 CPU: 9 UID: 0 PID: 117 Comm: kworker/9:1 Not tainted 6.13.0-rc1-work-00182-gb8f52214c61a-dirty #48 Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS unknown 02/02/2022 Workqueue: cgwb_release cgwb_release_workfn Call Trace: <TASK> dump_stack_lvl+0x27/0x80 print_report+0x151/0x710 kasan_report+0xc0/0x100 blkcg_unpin_online+0x15a/0x270 cgwb_release_workfn+0x194/0x480 process_scheduled_works+0x71b/0xe20 worker_thread+0x82a/0xbd0 kthread+0x242/0x2c0 ret_from_fork+0x33/0x70 ret_from_fork_asm+0x1a/0x30 </TASK> ... Freed by task 1944: kasan_save_track+0x2b/0x70 kasan_save_free_info+0x3c/0x50 __kasan_slab_free+0x33/0x50 kfree+0x10c/0x330 css_free_rwork_fn+0xe6/0xb30 process_scheduled_works+0x71b/0xe20 worker_thread+0x82a/0xbd0 kthread+0x242/0x2c0 ret_from_fork+0x33/0x70 ret_from_fork_asm+0x1a/0x30 Note that the UAF is not easy to trigger as the free path is indirected behind a couple RCU grace periods and a work item execution. I could only trigger it with artifical msleep() injected in blkcg_unpin_online(). Fix it by reading the parent pointer before destroying the blkcg's blkg's.

Lifecycle

Complete event history — 3 events, chronological
DateEventDetail
December 27, 2024ReservedReserved by Linux
December 27, 2024PublishedPublished (CNA: Linux)
October 15, 2026RESCOREDRESCORED — CVE-2024-56672 (Linux). CVSS 7.8 → 7 (NVD).

Affected

Affected products and packages — 2 rows
VendorProduct / PackageEcosystemVersion introducedFixed
LinuxLinux—4308a434e5e08c78676aa66bc626ef78cbef0883—
LinuxLinux—5.75.10.234

Weaknesses

CWE-416

References (9)

Related

Authoritative record: CVE-2024-56672 at cve.org

Vendors: linux

Weaknesses: CWE-416

About this page

This is a reference page, not a dated page of record. It assembles the complete lifecycle of CVE-2024-56672 from the CVE Program record, NVD enrichment, the CISA KEV catalog, EPSS, and OSV advisories. The box score's numbers (CVSS, EPSS, KEV status) are current as of Monday, October 19, 2026 UTC and are re-derived as the archive grows; only dated daily editions are immutable pages of record. The authoritative source for this identifier is cve.org.