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).
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
| Date | Event | Detail |
| December 27, 2024 | Reserved | Reserved by Linux |
| December 27, 2024 | Published | Published (CNA: Linux) |
| October 15, 2026 | RESCORED | RESCORED — CVE-2024-56672 (Linux). CVSS 7.8 → 7 (NVD). |
Affected
Affected products and packages — 2 rows
| Vendor | Product / Package | Ecosystem | Version introduced | Fixed |
| Linux | Linux | — | 4308a434e5e08c78676aa66bc626ef78cbef0883 | — |
| Linux | Linux | — | 5.7 | 5.10.234 |
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.