high CVSS 7.8 Actively exploited EPSS 1.3%

CVE-2025-38352·Kernel vulnerability

In the Linux kernel, the following vulnerability has been resolved: posix-cpu-timers: fix race between handle_posix_cpu_timers() and posix_cpu_timer_del() If an exiting non-autoreaping task has already passed exit_notify() and calls handle_posix_cpu_timers() from IRQ, it can be reaped by its parent or debugger right after unlock_task_sighand(). If a concurrent posix_cpu_timer_del() runs at that moment, it won't be able to detect timer->it.cpu.firing != 0: cpu_timer_task_rcu() and/or lock_task_sighand() will fail. Add the tsk->exit_state check into run_posix_cpu_timers() to fix this. This fix is not needed if CONFIG_POSIX_CPU_TIMERS_TASK_WORK=y, because exit_task_work() is called before exit_notify(). But the check still makes sense, task_work_add(&tsk->posix_cputimers_work.work) will fail anyway in this case.

Severity
high
Software
Kernel
Fixed in
6.15.3
Published

How likely is exploitation

FIRST's Exploit Prediction Scoring System puts the probability of this CVE being exploited in the next 30 days at 1.3% — higher than 69% of all published CVEs. EPSS is an independent forecast of exploitation, not a severity rating: it says nothing about how much damage a successful attack does, which is what a CVSS score measures.

Affected versions

From: 6.13

Until: 6.15.3

Fixed in: 6.15.3

How to fix this CVE

Update your Linux kernel to version 6.15.3 or later to resolve a critical race condition in POSIX CPU timer handling. This vulnerability allows privilege escalation when a non-autoreaping task exits while handling timers concurrently with timer deletion operations. Apply the kernel update immediately and reboot your system to fully mitigate the risk.

sudo dnf update kernel kernel-devel

Defensia detects this vulnerability

How to check if you are affected

  1. Check installed kernel version: uname -r — ensure version is 6.15.3 or later
  2. Verify POSIX CPU timers are active: grep CONFIG_POSIX_CPU_TIMERS /boot/config-$(uname -r) | grep -q '^CONFIG_POSIX_CPU_TIMERS=y' && echo 'POSIX timers enabled'
  3. Search kernel logs for timer-related errors: dmesg | grep -i 'posix.*timer\|cpu.*timer' — look for segfaults or locking failures
  4. Confirm patch application: git log --oneline /path/to/kernel/source | grep -i '2c72fe18\|2f3daa04\|460188bc' to verify the fix commit is present

FAQ

What is CVE-2025-38352?

CVE-2025-38352 is a race condition in the Linux kernel's POSIX CPU timer subsystem that occurs when a process exits while timer handlers and timer deletion operations execute concurrently, potentially leading to privilege escalation and system compromise.

Is CVE-2025-38352 being actively exploited?

Yes, CVE-2025-38352 is actively exploited in the wild and is listed in CISA's Known Exploited Vulnerabilities (KEV) catalog. No public exploit proof-of-concept has been disclosed, but active exploitation campaigns have been observed.

What versions of Kernel are affected by CVE-2025-38352?

Kernel versions 6.13 through 6.15.2 are vulnerable. Version 6.15.3 and later contain the fix. Systems running LTS kernels (5.15, 6.1, 6.6) are not affected unless they backport vulnerable timer code.

How do I check if my server is vulnerable to CVE-2025-38352?

Run `uname -r` to display your kernel version. If the output shows 6.13.x, 6.14.x, or 6.15.0-6.15.2, your system is vulnerable and requires immediate patching.

Does Defensia detect CVE-2025-38352?

Yes — Defensia's CVE advisory scanner compares installed package versions against the NVD database. If Kernel is installed on a monitored server, CVE-2025-38352 will appear in your dashboard with remediation steps.

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CVE-2026-64125CVSS 9.8In the Linux kernel, the following vulnerability has been resolved: net: bcmgenet: keep RBUF EEE/PM disabled Setting RBUF_EEE_EN | RBUF_PM_EN in RBUF_ENERGY_CTRL breaks the RX path on GENET hardware once MAC EEE becomes active. RX traffic stops flowing while the link stays up and the usual descriptor/RX error counters remain quiet. In that state the MAC still accepts frames (rbuf_ovflow_cnt keeps climbing) but RBUF no longer forwards them to DMA, so rx_packets is no longer incremented at the netdev level. On some boards the corruption ends up as a paging fault in skb_release_data via bcmgenet_rx_poll on an LPI exit. Reproduced on Pi 4B (BCM2711 + BCM54213PE) and confirmed by Florian Fainelli on an internal Broadcom 4908-family board with the same crash signature. RBUF_PM_EN is not publicly documented. This shows up more often now that phy_support_eee() enables EEE by default, but it also affects older kernels as soon as TX LPI is turned on via ethtool, so it is not specific to recent changes. Always clear RBUF_EEE_EN | RBUF_PM_EN in bcmgenet_eee_enable_set so the bits stay off across resets. UMAC and TBUF setup is left alone so TX-side EEE keeps working.
CVE-2026-64136CVSS 9.8In the Linux kernel, the following vulnerability has been resolved: smb: client: protect tc_count increment in smb2_find_smb_sess_tcon_unlocked() Commit 96c4af418586 ("cifs: Fix locking usage for tcon fields") refactored cifs code to change cifs_tcp_ses_lock for tc_lock around tc_count changes. There was missing lock around tc_count increment inside smb2_find_smb_sess_tcon_unlocked().
CVE-2026-53399CVSS 9.8In the Linux kernel, the following vulnerability has been resolved: nfsd: release layout stid on setlease failure nfs4_alloc_stid() publishes the new stid into cl->cl_stateids via idr_alloc_cyclic() under cl_lock before returning to nfsd4_alloc_layout_stateid(). When nfsd4_layout_setlease() then fails, the error path frees the layout stateid directly with kmem_cache_free() without ever calling idr_remove(), leaving the IDR slot pointing at freed slab memory. Any subsequent IDR walker (states_show, client teardown) dereferences the dangling pointer. The correct teardown for an IDR-published stid is nfs4_put_stid(), which removes the IDR slot under cl_lock, dispatches sc_free (nfsd4_free_layout_stateid) to release ls->ls_file via nfsd4_close_layout(), and drops the nfs4_file reference in its tail. A second issue blocks that switch: nfsd4_free_layout_stateid() unconditionally inspects ls->ls_fence_work via delayed_work_pending() under ls_lock, but INIT_DELAYED_WORK(&ls->ls_fence_work, ...) currently runs only after the setlease call. On the setlease-failure path the destructor would touch an uninitialized delayed_work. nfsd4_alloc_layout_stateid() nfs4_alloc_stid() /* idr_alloc_cyclic under cl_lock */ nfsd4_layout_setlease() /* fails */ nfs4_put_stid() nfsd4_free_layout_stateid() delayed_work_pending(&ls->ls_fence_work) /* needs INIT */ nfsd4_close_layout() /* nfsd_file_put(ls->ls_file) */ put_nfs4_file() Fix by hoisting the ls_fenced / ls_fence_delay / INIT_DELAYED_WORK initialization above the nfsd4_layout_setlease() call, and replace the manual nfsd_file_put + put_nfs4_file + kmem_cache_free cleanup with a single nfs4_put_stid(stp).

References

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