Linux kernel pid_namespace TIF_NOTIFY_SIGNAL reaper race
CVE-2026-99244 Published on November 3, 2026
pid_namespace: prevent TIF_NOTIFY_SIGNAL from interrupting the reaper
In the Linux kernel, the following vulnerability has been resolved:
pid_namespace: prevent TIF_NOTIFY_SIGNAL from interrupting the reaper
Since commit 7fea700e04bd ("zap_pid_ns_processes: clear
TIF_NOTIFY_SIGNAL along with TIF_SIGPENDING") zap_pid_ns_processes()
clears TIF_NOTIFY_SIGNAL before every kernel_wait4() call. Otherwise
kernel_wait4() doesn't sleep and returns -ERESTARTSYS if
signal_pending() is true and the reaper busy-waits.
But clearing TIF_NOTIFY_SIGNAL doesn't fix it. It can get raised again.
For example, klp_send_signals() sets it raw against any task that hasn't
transitioned yet. And it keeps sending it until the livepatch finishes.
The sleep loop waiting for pid_allocated to drop has the same problem
and it doesn't even clear anything. So a schedule() in
TASK_INTERRUPTIBLE returns immediately.
Use a no_notify_signal guard. signal_pending() will ignore
TIF_NOTIFY_SIGNAL and the pid namespace reaper sleeps until a child
exits or free_pid() wakes it.
Products Associated with CVE-2026-99244
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Affected Versions
Linux:- Version edd2754a62bee8d97b4808a15de024f66a1ddccf and below 2c20ace1698d03a23467351be1d281e89b36ade3 is affected.
- Version 3466abafa9f4f81a869da828e52a12f693175ec2 and below 9ab0324f4868eeb20c63f063a1e5bc01d5539212 is affected.
- Version 7fea700e04bd3f424c2d836e98425782f97b494e and below 30b274508c743f243c82904954c4e416d7143d4c is affected.
- Version 7fea700e04bd3f424c2d836e98425782f97b494e and below 70178691c467c8f9f722765299fd8524c3121a35 is affected.
- Version 7fea700e04bd3f424c2d836e98425782f97b494e and below 3d15ac36ce174477efa5365e424dbd47950fd2b9 is affected.
- Version 7fea700e04bd3f424c2d836e98425782f97b494e and below f46cd8241d9b83f2279cc0db3e9d3e181b548a59 is affected.
- Version 82c7acf9a12c9b4e4b0aba531de82b4e39a345c8 is affected.
- Version 8e69e589f233ca2c9631f5af2b94f95dfc2ba804 is affected.
- Version 09ab5b424b17cfe633db58bb2f9edbaf9484cf20 is affected.
- Version 6.1.95 and below 6.1.191 is affected.
- Version 6.6.35 and below 6.6.161 is affected.
- Version 5.10.221 and below 5.11 is affected.
- Version 5.15.162 and below 5.16 is affected.
- Version 6.9.6 and below 6.10 is affected.
- Version 6.10 is affected.
- Before 6.10 is unaffected.
- Version 6.1.191, <= 6.1.* is unaffected.
- Version 6.6.161, <= 6.6.* is unaffected.
- Version 6.12.115, <= 6.12.* is unaffected.
- Version 6.18.60, <= 6.18.* is unaffected.
- Version 7.2.14, <= 7.2.* is unaffected.
- Version 7.3.1, <= 7.3.* is unaffected.