CVE-2026-89655
CriticalCVSS 9.8Exploitation Probability (EPSS)
Low risk10th percentile - higher than 10% of all known CVEs
Summary
In the Linux kernel, the __kick_flushing_caps() function in the ceph module contains a use-after-free vulnerability. The function iterates over the i_cap_flush_list but drops the i_ceph_lock while sending cap messages, allowing handle_cap_flush_ack() to free a cf entry that the original thread later dereferences after reacquiring the lock.
Risk Assessment
This can lead to kernel memory corruption, system crash (panic), or potential arbitrary code execution with kernel privileges. It affects systems using the Ceph client in the Linux kernel.
Recommendation
Update the Linux kernel to a version containing the fix that converts the list_for_each_entry() loop to a manual while loop saving the next pointer before dropping the lock. If updating is not possible, consider limiting the use of the in-kernel Ceph client.
Other vulnerabilities in Linux kernel
See all- CVE-2026-80923Unknown
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- CVE-2026-80922Unknown
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- CVE-2026-80920Unknown
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- CVE-2026-80919Unknown
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- CVE-2026-80918Unknown
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- CVE-2026-80917Unknown
A vulnerability in the Linux kernel causes a NULL pointer dereference in the PCI host-generic driver on 32-bit systems using CAM mode. During PCI bus enumeration, the first config read uses an uninitialized mapping, leading to a kernel panic. The issue stems from missing add_bus/remove_bus callbacks in the CAM operations, which are necessary for proper mapping of the config space.
- CVE-2026-80916Unknown
A vulnerability in the Linux kernel's KCOV mechanism causes data corruption and race conditions on PREEMPT_RT systems. The issue stems from storing temporary KCOV state in per-CPU areas, which can be overwritten by nested softirq preemption. Additionally, under certain initialization conditions, it may lead to kernel panic or memory leaks.
- CVE-2026-80915Unknown
In the Linux kernel, the drm/xe driver's DPT allocation paths were fixed. The fallback from VRAM to system memory was removed as it did not work and caused black screen with pipe faults. Also, stolen memory usage is avoided due to latency and risk of random system hangs under load.
- CVE-2026-80886Unknown
In the Linux kernel, a vulnerability in the msm serial driver was fixed by disabling DMA for the console UART. Concurrent writes from userspace and the kernel can trigger a race condition resulting in an infinite loop of the same messages. The fix disables DMA for the console UART to ensure a reliable output path.
- CVE-2026-80885Unknown
In the Linux kernel, a fix was made for an uncancelled rxrpc OOB message handler in AFS. The fix cancels OOB message processing (typically to respond to security challenges) and moves it to afs_wq so it is also waited for. The OOB handler now returns if the net namespace is no longer live.
Original NVD description (English source)
In the Linux kernel, the following vulnerability has been resolved: ceph: fix UAF in __kick_flushing_caps() on cf entry freed during unlock list_for_each_entry() iterates ci->i_cap_flush_list but drops i_ceph_lock to send cap messages. During the unlock window, handle_cap_flush_ack() can acquire i_ceph_lock, detach cf entries with tid <= flush_tid from the list, release i_ceph_lock, and free them via ceph_free_cap_flush() outside any lock. When the original thread reacquires i_ceph_lock and the for-loop macro advances via cf = list_next_entry(cf, i_list), it dereferences cf->i_list.next on freed memory. The race timeline: __kick_flushing_caps() handle_cap_flush_ack() ----------------------- ----------------------- holds i_ceph_lock <--- iterates to cf (tid=10) prepares FLUSH message drops i_ceph_lock <--- __send_cap() ── FLUSH(tid=10) MDS sends FLUSH_ACK(tid=10) ---> acquires i_ceph_lock cf->tid(10) <= flush_tid(10), detaches cf from i_cap_flush_list drops i_ceph_lock ceph_free_cap_flush(cf) <- frees it! acquires i_ceph_lock <--- for-loop advances: cf = list_next_entry(cf, i_list) -- UAF on freed cf->i_list.next The cf was just sent by __kick_flushing_caps itself via __send_cap(). The MDS may respond with FLUSH_ACK quickly enough that handle_cap_flush_ack() frees cf before __kick_flushing_caps can finish the iteration. Fix by converting to a manual while loop: save the next pointer under i_ceph_lock before dropping it, then use the saved pointer after reacquiring, so the potentially-freed cf is never accessed again.