CVE-2026-23371

published 2026-03-25

CVE-2026-23371: In the Linux kernel, the following vulnerability has been resolved: sched/deadline: Fix missing ENQUEUE_REPLENISH during PI de-boosting Running stress-ng…

Priority P4 20 medium 5.5 CVSS 3.1

AV L AC L PR L UI N S U C N I N A H

In the Linux kernel, the following vulnerability has been resolved:

sched/deadline: Fix missing ENQUEUE_REPLENISH during PI de-boosting

Running stress-ng --schedpolicy 0 on an RT kernel on a big machine
might lead to the following WARNINGs (edited).

sched: DL de-boosted task PID 22725: REPLENISH flag missing

WARNING: CPU: 93 PID: 0 at kernel/sched/deadline.c:239 dequeue_task_dl+0x15c/0x1f8
... (running_bw underflow)
Call trace:
dequeue_task_dl+0x15c/0x1f8 (P)
dequeue_task+0x80/0x168
deactivate_task+0x24/0x50
push_dl_task+0x264/0x2e0
dl_task_timer+0x1b0/0x228
__hrtimer_run_queues+0x188/0x378
hrtimer_interrupt+0xfc/0x260
...

The problem is that when a SCHED_DEADLINE task (lock holder) is
changed to a lower priority class via sched_setscheduler(), it may
fail to properly inherit the parameters of potential DEADLINE donors
if it didn't already inherit them in the past (shorter deadline than
donor's at that time). This might lead to bandwidth accounting
corruption, as enqueue_task_dl() won't recognize the lock holder as
boosted.

The scenario occurs when:
1. A DEADLINE task (donor) blocks on a PI mutex held by another
DEADLINE task (holder), but the holder doesn't inherit parameters
(e.g., it already has a shorter deadline)
2. sched_setscheduler() changes the holder from DEADLINE to a lower
class while still holding the mutex
3. The holder should now inherit DEADLINE parameters from the donor
and be enqueued with ENQUEUE_REPLENISH, but this doesn't happen

Fix the issue by introducing __setscheduler_dl_pi(), which detects when
a DEADLINE (proper or boosted) task gets setscheduled to a lower
priority class. In case, the function makes the task inherit DEADLINE
parameters of the donoer (pi_se) and sets ENQUEUE_REPLENISH flag to
ensure proper bandwidth accounting during the next enqueue operation.

Affected

17 ranges

Vendor	Product	Version range	Fixed in
debian	linux	< linux 6.19.8-1 (forky)	linux 6.19.8-1 (forky)
linux	linux	—	—
linux	linux	—	—
linux	linux	—	—
linux	linux	>= 2279f540ea7d05f22d2f0c4224319330228586bc < 0638bf16b7a73a2fe63624bd0d16d9fd904805c3	0638bf16b7a73a2fe63624bd0d16d9fd904805c3
linux	linux	>= 2279f540ea7d05f22d2f0c4224319330228586bc < ba1c22924ddcc280672a2a06a9ca99ee3a1b92c3	ba1c22924ddcc280672a2a06a9ca99ee3a1b92c3
linux	linux	>= 2279f540ea7d05f22d2f0c4224319330228586bc < d658686a1331db3bb108ca079d76deb3208ed949	d658686a1331db3bb108ca079d76deb3208ed949
linux	linux	>= 4.19.257 < 4.20	4.20
linux	linux	>= 5.4.212 < 5.5	5.5
linux	linux_kernel	—	—
linux	linux_kernel	—	—
linux	linux_kernel	>= 0 < 6.19.8-1	6.19.8-1
linux	linux_kernel	>= 4.19.257 < 4.20	4.20
linux	linux_kernel	>= 5.10.0 < 6.19.7	6.19.7
linux	linux_kernel	>= 5.10.1 < 6.19.7	6.19.7
linux	linux_kernel	>= 5.4.212 < 5.5	5.5
msrc	azl3_kernel_6.6.126.1-1_on_azure_linux_3.0	—	—

CVSS provenance

nvd v3.1 5.5 MEDIUM CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H

vendor_msrc 4.7 MEDIUM

Stop checking back — get the weekly exploitation signal.

Every Monday: what got weaponized or added to CISA KEV in the last seven days — each CVE cross-linked to its PoC, Nuclei template, and detection rule. Free, one email a week, unsubscribe in one click.

CWE-372