CVE-2026-89915
CriticalCVSS 9.3Summary
In the Linux kernel, the global VNCR mapping counter in KVM arm64 was removed. This counter was used to decide whether a TLB invalidation was needed, but it had flaws: checking it could cause missed TLB invalidations, and an L1 vcpu invalidating its own TLB would not invalidate the VNCR pseudo TLB. Since it failed to provide required guarantees, it was removed entirely.
Risk Assessment
Missed TLB invalidations can cause incorrect address translation in the guest VM and potential hypervisor faults. It affects KVM on arm64 environments.
Recommendation
Update the Linux kernel to a version containing the fix. Monitor kernel logs for KVM arm64 related errors.
Other vulnerabilities in Linux kernel
See all- CVE-2026-90046High
In the Linux kernel, free_pages_nolock() uses spin_trylock() in NMI context on uniprocessor (UP) systems, which is unsafe. The bug affects the page freeing path and can crash the kernel. It is likely exploitable by local attackers for privilege escalation.
- CVE-2026-90045High
In the Linux kernel USB gadget ffs driver, the io_data structure stores a pointer to the submitting task's mm_struct but does not hold a reference while async requests are pending. This can cause a use-after-free if the task exits before completion handling finishes. The fix takes a reference with mmgrab() when queuing and releases it with mmdrop() on completion.
- CVE-2026-90044High
In the Linux kernel USB gadget f_fs driver, a use-after-free exists in the AIO error path. When ffs_epfile_io() fails with an error other than -EIOCBQUEUED, the io_data structure is freed, but the kiocb cancel function remains armed and points to the freed pointer. A concurrent cancel (e.g., sys_io_cancel()) can cause a use-after-free. The fix safely disarms the cancellation via kiocb->ki_complete() and returns -EIOCBQUEUED.
- CVE-2026-90043High
In the Linux kernel zram module, the slot lock bit is set in the wrong position on 64-bit big-endian systems. Instead of landing in the flags field, it lands in ac_time, so with ZRAM_TRACK_ENTRY_ACTIME enabled, storing the access time wipes out the held lock bit and lets another CPU take the same slot lock. An access time value with that bit set can make the slot appear locked forever. The fix shifts the lock bit into the flags half on big-endian 64-bit.
- CVE-2026-90041High
In the Linux kernel, the HID sony driver fails to remove a controller from the device list when HID core input device registration fails. The devres-managed sony_sc is freed while its list node remains linked, leading to use-after-free when the next matching controller is handled.
- CVE-2026-90039Unknown
In the Linux kernel, NFSD admin state-revocation handlers (unlock_filesystem, NFSD_CMD_UNLOCK_FILESYSTEM, NFSD_CMD_UNLOCK_EXPORT) only check nn->nfsd_serv, which is set before nn->conf_id_hashtbl is allocated. This leads to a NULL dereference when the server has not yet started.
- CVE-2026-90035Unknown
In the Linux kernel, get_estimated_bw() in the drm/amd/display driver divides by bw_granularity, which is zeroed and only populated after DP_TUNNELING_BW_ALLOC_CAP_CHANGED is handled. If a USB4/DPIA device reports an estimated-bandwidth change before a capability change, the DPCD interrupt handler triggers a division by zero.
- CVE-2026-90034Unknown
In the Linux kernel, the usb image mdc800 driver uses kmalloc() for irq_urb_buffer and download_urb_buffer in usb_mdc800_init(). If a shorter message is received in mdc800_usb_irq() or mdc800_usb_download_notify(), stack data may leak.
- CVE-2026-90033Unknown
In the Linux kernel, snd_usbmidi_us122l_output() in ALSA usb-audio picks a count of 2 for anything slower than high speed without relating it to ep->max_transfer. With a device declaring a one-byte bulk endpoint, the memset computes 1 - 2 in int and wraps to SIZE_MAX, causing an out-of-bounds write.
- CVE-2026-90024Unknown
A null-pointer dereference vulnerability exists in the Linux kernel's USB gadget MIDI 2.0 function, specifically in f_midi2_free_ep_reqs(). When configuring a MIDI 2.0 gadget via configfs with block direction set to SNDRV_UMP_DIR_INPUT, the midi1_ep_out endpoint is not initialized, leaving usb_ep->card as NULL. When the host later sets the alternate setting, f_midi2_free_ep_reqs() is called for the uninitialized endpoint, causing a kernel crash.
Original NVD description (English source)
In the Linux kernel, the following vulnerability has been resolved: KVM: arm64: Remove VM-wide VNCR mapping counter The global VNCR mapping counter is used to decide whether an L1 provided VNCR page is mapped in L0 on any CPU at the point of dealing with a TLB invalidation. It is incremented when a mapping is made in the fixmap, and decremented when unmapped. As it turns out, this tracking has several flaws: - we are trying to invalidate TLBs, and the mapping is only an opportunistic consequence of the TLB. Checking this counter to decide whether a TLB needs to be invalidated may result in missed invalidations. - an L1 vcpu invalidating its own TLB (a very likely case) will not succeed in invalidating the VNCR pseudo TLB because that page is not mapped in L0 at this stage. Given that this tracking fails at delivering the minimum guarantees that are required and is only a performance optimisation, remove it completely.