Reference page — cumulative record through Wednesday, August 19, 2026 UTC. Reference pages update as the archive grows; only dated daily editions are immutable pages of record.
Linux Linux — io_uring/io-wq: Use set_bit() and test_bit() at worker->flags
AV AC PR UI S C I A CVSS EPSS %ile KEV
L H L N U N N H 4.7 .0022 13.3 —
AFFECTED
Product Versions Fixed
Linux 2b188cc1bb857a9d4701ae59aa7768b5124e262e – —
Linux 5.1 – 6.6.35
TIMELINE
Jun 25 Reserved by Linux
Jul 12 Published (CNA: Linux)
Aug 4 RESCORED — CVE-2024-39508 (Linux). CVSS 7.8 → 4.7 (NVD).
Description
In the Linux kernel, the following vulnerability has been resolved:
io_uring/io-wq: Use set_bit() and test_bit() at worker->flags
Utilize set_bit() and test_bit() on worker->flags within io_uring/io-wq
to address potential data races.
The structure io_worker->flags may be accessed through various data
paths, leading to concurrency issues. When KCSAN is enabled, it reveals
data races occurring in io_worker_handle_work and
io_wq_activate_free_worker functions.
BUG: KCSAN: data-race in io_worker_handle_work / io_wq_activate_free_worker
write to 0xffff8885c4246404 of 4 bytes by task 49071 on cpu 28:
io_worker_handle_work (io_uring/io-wq.c:434 io_uring/io-wq.c:569)
io_wq_worker (io_uring/io-wq.c:?)
<snip>
read to 0xffff8885c4246404 of 4 bytes by task 49024 on cpu 5:
io_wq_activate_free_worker (io_uring/io-wq.c:? io_uring/io-wq.c:285)
io_wq_enqueue (io_uring/io-wq.c:947)
io_queue_iowq (io_uring/io_uring.c:524)
io_req_task_submit (io_uring/io_uring.c:1511)
io_handle_tw_list (io_uring/io_uring.c:1198)
<snip>
Line numbers against commit 18daea77cca6 ("Merge tag 'for-linus' of
git://git.kernel.org/pub/scm/virt/kvm/kvm").
These races involve writes and reads to the same memory location by
different tasks running on different CPUs. To mitigate this, refactor
the code to use atomic operations such as set_bit(), test_bit(), and
clear_bit() instead of basic "and" and "or" operations. This ensures
thread-safe manipulation of worker flags.
Also, move `create_index` to avoid holes in the structure.
Lifecycle
Complete event history — 3 events, chronological
| Date | Event | Detail |
| June 25, 2024 | Reserved | Reserved by Linux |
| July 12, 2024 | Published | Published (CNA: Linux) |
| August 4, 2026 | RESCORED | RESCORED — CVE-2024-39508 (Linux). CVSS 7.8 → 4.7 (NVD). |
Affected
Affected products and packages — 2 rows
| Vendor | Product / Package | Ecosystem | Version introduced | Fixed |
| Linux | Linux | — | 2b188cc1bb857a9d4701ae59aa7768b5124e262e | — |
| Linux | Linux | — | 5.1 | 6.6.35 |
About this page
This is a reference page, not a dated page of record. It assembles the complete lifecycle of CVE-2024-39508 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 Wednesday, August 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.