CVE-2026-31586
published 2026-04-24CVE-2026-31586: In the Linux kernel, the following vulnerability has been resolved: mm: blk-cgroup: fix use-after-free in cgwb_release_workfn() cgwb_release_workfn() calls…
PriorityP342high7.8CVSS 3.1
AVLACLPRLUINSUCHIHAH
EPSS
0.13%
2.8th percentile
In the Linux kernel, the following vulnerability has been resolved:
mm: blk-cgroup: fix use-after-free in cgwb_release_workfn()
cgwb_release_workfn() calls css_put(wb->blkcg_css) and then later accesses
wb->blkcg_css again via blkcg_unpin_online(). If css_put() drops the last
reference, the blkcg can be freed asynchronously (css_free_rwork_fn ->
blkcg_css_free -> kfree) before blkcg_unpin_online() dereferences the
pointer to access blkcg->online_pin, resulting in a use-after-free:
BUG: KASAN: slab-use-after-free in blkcg_unpin_online (./include/linux/instrumented.h:112 ./include/linux/atomic/atomic-instrumented.h:400 ./include/linux/refcount.h:389 ./include/linux/refcount.h:432 ./include/linux/refcount.h:450 block/blk-cgroup.c:1367)
Write of size 4 at addr ff11000117aa6160 by task kworker/71:1/531
Workqueue: cgwb_release cgwb_release_workfn
Call Trace:
blkcg_unpin_online (./include/linux/instrumented.h:112 ./include/linux/atomic/atomic-instrumented.h:400 ./include/linux/refcount.h:389 ./include/linux/refcount.h:432 ./include/linux/refcount.h:450 block/blk-cgroup.c:1367)
cgwb_release_workfn (mm/backing-dev.c:629)
process_scheduled_works (kernel/workqueue.c:3278 kernel/workqueue.c:3385)
Freed by task 1016:
kfree (./include/linux/kasan.h:235 mm/slub.c:2689 mm/slub.c:6246 mm/slub.c:6561)
css_free_rwork_fn (kernel/cgroup/cgroup.c:5542)
process_scheduled_works (kernel/workqueue.c:3302 kernel/workqueue.c:3385)
** Stack based on commit 66672af7a095 ("Add linux-next specific files
for 20260410")
I am seeing this crash sporadically in Meta fleet across multiple kernel
versions. A full reproducer is available at:
https://github.com/leitao/debug/blob/main/reproducers/repro_blkcg_uaf.sh
(The race window is narrow. To make it easily reproducible, inject a
msleep(100) between css_put() and blkcg_unpin_online() in
cgwb_release_workfn(). With that delay and a KASAN-enabled kernel, the
reproducer triggers the splat reliably in less than a second.)
Fix this by moving blkcg_un
Affected
24 ranges
| Vendor | Product | Version range | Fixed in |
|---|---|---|---|
| linux | linux | — | — |
| linux | linux | >= 59b57717fff8b562825d9d25e0180ad7e8048ca9 < 23acef4156c260e8598397a1a2e8b3a23e919893 | 23acef4156c260e8598397a1a2e8b3a23e919893 |
| linux | linux | >= 59b57717fff8b562825d9d25e0180ad7e8048ca9 < 1bd36e93b542d9dd020190c6607c6a3663405195 | 1bd36e93b542d9dd020190c6607c6a3663405195 |
| linux | linux | >= 59b57717fff8b562825d9d25e0180ad7e8048ca9 < 740ba1ebb223f137ff088ab74d533a13f9167bd8 | 740ba1ebb223f137ff088ab74d533a13f9167bd8 |
| linux | linux | >= 59b57717fff8b562825d9d25e0180ad7e8048ca9 < 115a5266749dcde7fe4127e8623d19c752088f69 | 115a5266749dcde7fe4127e8623d19c752088f69 |
| linux | linux | >= 59b57717fff8b562825d9d25e0180ad7e8048ca9 < dfc8292a1d6782c76b626315605e0585a5a18447 | dfc8292a1d6782c76b626315605e0585a5a18447 |
| linux | linux | >= 59b57717fff8b562825d9d25e0180ad7e8048ca9 < ea3af09eb87d8f8708c66747fcf1a2762902e839 | ea3af09eb87d8f8708c66747fcf1a2762902e839 |
| linux | linux | >= 59b57717fff8b562825d9d25e0180ad7e8048ca9 < 50879a3c1faf06e661090015d59e2127255cff27 | 50879a3c1faf06e661090015d59e2127255cff27 |
| linux | linux | >= 59b57717fff8b562825d9d25e0180ad7e8048ca9 < 67cb119d32f35e32acd0393bbeb318b2bb1fdafe | 67cb119d32f35e32acd0393bbeb318b2bb1fdafe |
| linux | linux | >= 59b57717fff8b562825d9d25e0180ad7e8048ca9 < 8f5857be99f1ed1fa80991c72449541f634626ee | 8f5857be99f1ed1fa80991c72449541f634626ee |
| linux | linux_kernel | — | — |
| linux | linux_kernel | >= 4.19 < 6.6.136 | 6.6.136 |
| linux | linux_kernel | >= 6.13 < 6.18.24 | 6.18.24 |
| linux | linux_kernel | >= 6.19 < 6.19.14 | 6.19.14 |
| linux | linux_kernel | >= 6.7 < 6.12.83 | 6.12.83 |
| linux | linux_kernel | >= 7.0 < 7.0.1 | 7.0.1 |
| ubuntu | linux | — | — |
| ubuntu | linux-aws | — | — |
| ubuntu | linux-gcp | — | — |
| ubuntu | linux-ibm | — | — |
| ubuntu | linux-nvidia | — | — |
| ubuntu | linux-oracle | — | — |
| ubuntu | linux-raspi | — | — |
| ubuntu | linux-realtime | — | — |
CVSS provenance
nvdv3.17.8HIGHCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
vendor_redhat7.0HIGH
vendor_ubuntu2.0LOW
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Ubuntu
Linux kernel (NVIDIA) vulnerabilities
vendor_ubuntu·2026-07-06·CVSS 2.0
CVE-2026-46009 [LOW] Linux kernel (NVIDIA) vulnerabilities
Title: Linux kernel (NVIDIA) vulnerabilities
Summary: Several security issues were fixed in the Linux kernel.
It was discovered that some AMD processors did not properly clear data in
the floating point divider unit during speculative execution. A local
attacker could use this to expose sensitive information. (CVE-2025-54505)
Several security issues were discovered in the Linux kernel.
An attacker could possibly use these to compromise the system.
This update corrects flaws in the following subsystems:
- ARM64 architecture;
- x86 architecture;
- Block layer subsystem;
- Cryptographic API;
- Rados block device (RBD) driver;
- Compressed RAM block device driver;
- Character device driver;
- TPM device driver;
- Hardware crypto device drivers;
- EDAC drivers;
- GPU drivers;
- Greybus drive
Ubuntu
Linux kernel (Raspberry Pi) vulnerabilities
vendor_ubuntu·2026-07-02·CVSS 2.0
CVE-2026-46316 [LOW] Linux kernel (Raspberry Pi) vulnerabilities
Title: Linux kernel (Raspberry Pi) vulnerabilities
Summary: Several security issues were fixed in the Linux kernel.
It was discovered that some AMD processors did not properly clear data in
the floating point divider unit during speculative execution. A local
attacker could use this to expose sensitive information. (CVE-2025-54505)
Several security issues were discovered in the Linux kernel.
An attacker could possibly use these to compromise the system.
This update corrects flaws in the following subsystems:
- ARM64 architecture;
- x86 architecture;
- Block layer subsystem;
- Cryptographic API;
- Rados block device (RBD) driver;
- Compressed RAM block device driver;
- Character device driver;
- TPM device driver;
- Hardware crypto device drivers;
- EDAC drivers;
- GPU drivers;
- Greybus
Ubuntu
Linux kernel vulnerabilities
vendor_ubuntu·2026-07-01·CVSS 2.0
CVE-2026-46042 [LOW] Linux kernel vulnerabilities
Title: Linux kernel vulnerabilities
Summary: Several security issues were fixed in the Linux kernel.
It was discovered that some AMD processors did not properly clear data in
the floating point divider unit during speculative execution. A local
attacker could use this to expose sensitive information. (CVE-2025-54505)
Several security issues were discovered in the Linux kernel.
An attacker could possibly use these to compromise the system.
This update corrects flaws in the following subsystems:
- ARM64 architecture;
- x86 architecture;
- Block layer subsystem;
- Cryptographic API;
- Rados block device (RBD) driver;
- Compressed RAM block device driver;
- Character device driver;
- TPM device driver;
- Hardware crypto device drivers;
- EDAC drivers;
- GPU drivers;
- Greybus drivers;
- HID
Red Hat
kernel: mm: blk-cgroup: fix use-after-free in cgwb_release_workfn()
vendor_redhat·2026-04-24·CVSS 7.0
CVE-2026-31586 [HIGH] CWE-366 kernel: mm: blk-cgroup: fix use-after-free in cgwb_release_workfn()
kernel: mm: blk-cgroup: fix use-after-free in cgwb_release_workfn()
A flaw was found in the Linux kernel's block control group (blk-cgroup) component. A timing issue in the cgwb_release_workfn() function can lead to a use-after-free vulnerability. This occurs when a block control group object is prematurely released while still being referenced. A local attacker could exploit this to cause system instability or a denial of service.
Package: kernel (Red Hat Enterprise Linux 10) - Affected
Package: kernel (Red Hat Enterprise Linux 6) - Under investigation
Package: kernel (Red Hat Enterprise Linux 7) - Affected
Package: kernel-rt (Red Hat Enterprise Linux 7) - Affected
Package: kernel (Red Hat Enterprise Linux 8) - Affected
Package: kernel-rt (Red Hat Enterprise Linux 8) - Affected
Pa
GHSA
GHSA-x7q8-xcw2-7mfg: In the Linux kernel, the following vulnerability has been resolved:
mm: blk-cgroup: fix use-after-free in cgwb_release_workfn()
cgwb_release_workfn(
ghsa_unreviewed·2026-04-24
CVE-2026-31586 GHSA-x7q8-xcw2-7mfg: In the Linux kernel, the following vulnerability has been resolved:
mm: blk-cgroup: fix use-after-free in cgwb_release_workfn()
cgwb_release_workfn(
In the Linux kernel, the following vulnerability has been resolved:
mm: blk-cgroup: fix use-after-free in cgwb_release_workfn()
cgwb_release_workfn() calls css_put(wb->blkcg_css) and then later accesses
wb->blkcg_css again via blkcg_unpin_online(). If css_put() drops the last
reference, the blkcg can be freed asynchronously (css_free_rwork_fn ->
blkcg_css_free -> kfree) before blkcg_unpin_online() dereferences the
pointer to access blkcg->online_pin, resulting in a use-after-free:
BUG: KASAN: slab-use-after-free in blkcg_unpin_online (./include/linux/instrumented.h:112 ./include/linux/atomic/atomic-instrumented.h:400 ./include/linux/refcount.h:389 ./include/linux/refcount.h:432 ./include/linux/refcount.h:450 block/blk-cgroup.c:1367)
Write of size 4 at addr ff11000117aa6160 by task kwork
No detection rules found.
No public exploits indexed.
https://git.kernel.org/stable/c/115a5266749dcde7fe4127e8623d19c752088f69https://git.kernel.org/stable/c/1bd36e93b542d9dd020190c6607c6a3663405195https://git.kernel.org/stable/c/23acef4156c260e8598397a1a2e8b3a23e919893https://git.kernel.org/stable/c/50879a3c1faf06e661090015d59e2127255cff27https://git.kernel.org/stable/c/67cb119d32f35e32acd0393bbeb318b2bb1fdafehttps://git.kernel.org/stable/c/740ba1ebb223f137ff088ab74d533a13f9167bd8https://git.kernel.org/stable/c/8f5857be99f1ed1fa80991c72449541f634626eehttps://git.kernel.org/stable/c/dfc8292a1d6782c76b626315605e0585a5a18447https://git.kernel.org/stable/c/ea3af09eb87d8f8708c66747fcf1a2762902e839
2026-04-24
Published