Linux kernel PID namespace reaper interrupted by TIF_NOTIFY_SIGNAL
Key facts
- Attack vector
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- Privileges required
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- User interaction
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- Attack complexity
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- Impact type
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- Confidentiality · integrity · availability
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- Fix status
- Partial Red Hat: 3 without a fix
No CVSS vector from any source. Fix status from CNA and Red Hat.
Summary
Linux kernel versions 6.1.95 before 6.1.191, 6.6.35 before 6.6.161, 5.10.221 before 5.11, 5.15.162 before 5.16, 6.9.6 before 6.10, and from 6.10 onward are affected. The PID namespace reaper clears TIF_NOTIFY_SIGNAL before waiting, but livepatch signaling can raise the flag again, so the reaper busy-waits instead of sleeping. The sleep loop waiting for pid_allocated has the same problem, so schedule returns immediately.
Written with Claude Haiku 5.5 from the sources below · 2026-11-04
Description from the CNA
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.
Why it matters now
SSVC decision points
Not available: CISA has not published SSVC decision points for this record.
Affected products
| Vendor | Product | Affected versions | Fixed in | Status | Source |
|---|---|---|---|---|---|
| Linux | Linux | 6.1.95 to before 6.1.191; 6.6.35 to before 6.6.161; 5.10.221 to before 5.11; 5.15.162 to before 5.16; 6.9.6 to before 6.10 | 6.1.191, 6.6.161, 5.11, 5.16, 6.10 | Patch available | CNA |
| Linux | Linux | 6.10 and later | 6.1.191, 6.6.161, 6.12.115, 6.18.60, 7.2.14, 7.3.1, 7.4-rc1 | Patch available | CNA |
- Linux VendorLinux Affected 6.1.95 to before 6.1.191; 6.6.35 to before 6.6.161; 5.10.221 to before 5.11; 5.15.162 to before 5.16; 6.9.6 to before 6.10 Fixed in 6.1.191, 6.6.161, 5.11, 5.16, 6.10 Patch available CNA
- Linux VendorLinux Affected 6.10 and later Fixed in 6.1.191, 6.6.161, 6.12.115, 6.18.60, 7.2.14, 7.3.1, 7.4-rc1 Patch available CNA
Remediation
For the Linux kernel, fixed versions are 5.11, 5.16, 6.1.191, 6.6.161, 6.10, 6.12.115, 6.18.60, 7.2.14, 7.3.1 and 7.4-rc1. Red Hat lists Red Hat Enterprise Linux 10 and Red Hat OpenShift Container Platform 5 with no fix available, and Red Hat Enterprise Linux 6 with no fix planned.
Written with Claude Haiku 5.5 from the sources below · 2026-11-04
- Fix · CNA Linux (Linux) Fixed in 6.1.191, 6.6.161, 5.11, 5.16, 6.10
- Fix · CNA Linux (Linux) Fixed in 6.1.191, 6.6.161, 6.12.115, 6.18.60, 7.2.14, 7.3.1, 7.4-rc1
Vendor assessments
Red Hat
Red Hat rating: Low. Red Hat's page for this CVE →
| Product | Status | Plan or fix |
|---|---|---|
| Red Hat Enterprise Linux 10 | Affected | No fix yet: Fix deferred |
| Red Hat Enterprise Linux 6 | Affected | No fix planned: Out of support scope |
| Red Hat OpenShift Container Platform 5 | Affected | No fix yet: Fix deferred |
Not affected: 5 products
- Red Hat Enterprise Linux 7
- Red Hat Enterprise Linux 8
- Red Hat Enterprise Linux 9
- Red Hat OpenShift Container Platform 4
- Red Hat OpenShift Container Platform 5
Timeline
- 2026-11-03 Threatist record created from CVE-2026-99244
- 2026-11-03 Alias added: GHSA-7cwf-57xm-qrxg
- 2026-11-03 Fix available: Linux/Linux@5c0985dd3c32fc2bbd0e8beaf13cf52cd97376a2, Linux/[email protected] · CNA
- 2026-11-03 1 new reference · CNA
- 2026-11-04 Affected versions changed · Red Hat
- 2026-11-04 CVSS score added · Red Hat
References
Other 7
- https://git.kernel.org/stable/c/2c20ace1698d03a23467351be1d281e89b36ade3
- https://git.kernel.org/stable/c/9ab0324f4868eeb20c63f063a1e5bc01d5539212
- https://git.kernel.org/stable/c/30b274508c743f243c82904954c4e416d7143d4c
- https://git.kernel.org/stable/c/70178691c467c8f9f722765299fd8524c3121a35
- https://git.kernel.org/stable/c/3d15ac36ce174477efa5365e424dbd47950fd2b9
- https://git.kernel.org/stable/c/f46cd8241d9b83f2279cc0db3e9d3e181b548a59
- https://git.kernel.org/stable/c/5c0985dd3c32fc2bbd0e8beaf13cf52cd97376a2
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Sources
- CVE-2026-99244 · CVE Program
- CVE-2026-99244 · NVD
- FIRST EPSS
- GHSA-7cwf-57xm-qrxg · GitHub Advisory Database · CC BY 4.0
- CVE-2026-99244 · Red Hat security data · CC BY 4.0
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