CVE-2026-99249

pid_namespace: make zap_pid_ns_processes() freezable

Published Nov 3, 2026 CVSS n/a EPSS < 1% KEV · Not listed
Description
In the Linux kernel, the following vulnerability has been resolved:

pid_namespace: make zap_pid_ns_processes() freezable

When the init of a pid namespace exits, zap_pid_ns_processes() waits
until all other pids in the namespace are freed. A tracer outside the
namespace that does not reap its traced zombies keeps those pids
allocated, so this wait has no upper bound, and while it lasts every
suspend attempt fails:

Freezing user space processes failed after 20.006 seconds (2 tasks refusing to freeze, wq_busy=0):

Neither wait is freezable. The first loop sleeps in do_wait(), which
returns -ERESTARTSYS on the freezer's fake signal; the loop then clears
TIF_SIGPENDING and waits again without ever freezing. The final loop
sleeps in TASK_INTERRUPTIBLE, and since nothing clears TIF_SIGPENDING
there, schedule() returns immediately after the first freeze attempt
and the task spins until the wait ends.

Sleep in TASK_INTERRUPTIBLE | TASK_FREEZABLE in do_wait(), so that the
freezer can freeze tasks waiting there directly, and in TASK_IDLE |
TASK_FREEZABLE in the final loop, like coredump_task_exit() does.

This was hit with Chromium-based browsers: crashpad ptrace-attaches the
threads of a crashed renderer, which is a pid namespace init, and does
not reap those killed during the dump.

Remediation

No solution or workaround provided in the CVE record

Tracking

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Advisories

Source ID Title
Debian DLA Debian DLA DLA-4904-1 linux-6.12 security update
History
Type Values Removed Values Added
Weaknesses CWE-665
Type Values Removed Values Added
First Time appeared Linux linux
Vendors & Products Linux linux
Type Values Removed Values Added
Description In the Linux kernel, the following vulnerability has been resolved: pid_namespace: make zap_pid_ns_processes() freezable When the init of a pid namespace exits, zap_pid_ns_processes() waits until all other pids in the namespace are freed. A tracer outside the namespace that does not reap its traced zombies keeps those pids allocated, so this wait has no upper bound, and while it lasts every suspend attempt fails: Freezing user space processes failed after 20.006 seconds (2 tasks refusing to freeze, wq_busy=0): Neither wait is freezable. The first loop sleeps in do_wait(), which returns -ERESTARTSYS on the freezer's fake signal; the loop then clears TIF_SIGPENDING and waits again without ever freezing. The final loop sleeps in TASK_INTERRUPTIBLE, and since nothing clears TIF_SIGPENDING there, schedule() returns immediately after the first freeze attempt and the task spins until the wait ends. Sleep in TASK_INTERRUPTIBLE | TASK_FREEZABLE in do_wait(), so that the freezer can freeze tasks waiting there directly, and in TASK_IDLE | TASK_FREEZABLE in the final loop, like coredump_task_exit() does. This was hit with Chromium-based browsers: crashpad ptrace-attaches the threads of a crashed renderer, which is a pid namespace init, and does not reap those killed during the dump.
Title pid_namespace: make zap_pid_ns_processes() freezable
First Time appeared Linux
Linux linux Kernel
CPEs cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*
Vendors & Products Linux
Linux linux Kernel
References
Weaknesses

Sources

Status
PUBLISHED
Assigner
Linux
Published
Updated
Nov 3, 2026, 11:18 AM
Reserved
Sep 25, 2026, 10:25 AM
Status
Received
Published
Nov 3, 2026, 12:17 PM
Modified
Nov 3, 2026, 12:17 PM