RLSA-2026:45115 Important: kernel security update

The kernel packages contain the Linux kernel, the core of any Linux operating system. Security Fixes: kernel: KVM: x86: Don't recheck L1 intercepts when completing userspace I/O CVE-2025-40026 kernel: xfrm single-frag length not properly limited kernel: dm log: fix out-of-bounds write due to...

CVE-2026-10681

In Zephyr's userspace dynamic-objects subsystem, threadidxalloc in kernel/userspace/userspace.c allocated a new thread permission index from the global threadidxmap bitmap without holding listslock. On SMP systems, two user-mode threads invoking the kobjectallocKOBJTHREAD syscall concurrently can...

CVE-2026-10681 SMP race in `thread_idx_alloc()` lets concurrent `k_object_alloc(K_OBJ_THREAD)` callers share a kernel-object permission slot

In Zephyr's userspace dynamic-objects subsystem, threadidxalloc in kernel/userspace/userspace.c allocated a new thread permission index from the global threadidxmap bitmap without holding listslock. On SMP systems, two user-mode threads invoking the kobjectallocKOBJTHREAD syscall concurrently can...

CVE-2026-10681 SMP race in `thread_idx_alloc()` lets concurrent `k_object_alloc(K_OBJ_THREAD)` callers share a kernel-object permission slot

In Zephyr's userspace dynamic-objects subsystem, threadidxalloc in kernel/userspace/userspace.c allocated a new thread permission index from the global threadidxmap bitmap without holding listslock. On SMP systems, two user-mode threads invoking the kobjectallocKOBJTHREAD syscall concurrently can...

CVE-2026-10681

The CVE-2026-10681 issue affects Zephyr's userspace dynamic-objects subsystem. In thread_idx_alloc(), a new thread permission index is taken from _thread_idx_map[] without holding lists_lock. On SMP, concurrent k_object_alloc(K_OBJ_THREAD) calls can observe the same lowest free bit and perform a ...

EUVD-2026-48871

In the Linux kernel, the following vulnerability has been resolved: usb: gadget: ffs: Initialize epfile-in early to fix endpoint direction checks When parsing endpoint descriptors, ffsdatagotdescs generates the epsaddrmap which contains the endpoint direction. However, epfile-in was previously on...

CVE-2026-64327

The CVE-2026-64327 in the Linux kernel affects usb: gadget: f_fs. The vulnerability occurred because epfile->in was initialized only in ffs_func_eps_enable(), which runs after USB host connection. Early userspace IOCTLs could observe epfile->in as 0, causing incorrect DMA directions. The fi...

CVE-2026-64327 usb: gadget: f_fs: Initialize epfile->in early to fix endpoint direction checks

In the Linux kernel, the following vulnerability has been resolved: usb: gadget: ffs: Initialize epfile-in early to fix endpoint direction checks When parsing endpoint descriptors, ffsdatagotdescs generates the epsaddrmap which contains the endpoint direction. However, epfile-in was previously on...

EUVD-2026-48996

In the Linux kernel, the following vulnerability has been resolved: KVM: x86: Ensure vendor's exit handler runs before fastpath userspace exits Move the handling of fastpath userspace exits into vendor code to ensure KVM runs vendor specific operations that need to run before userspace gains...

CVE-2026-64284

CVE-2026-64284 — Linux kernel (KVM/x86): The vulnerability involves moving the handling of fastpath userspace exits into vendor code so KVM can run vendor-specific operations before userspace gains control of the vCPU. The description notes that, for VMX (and soon SVM), KVM must flush the PML buf...

CVE-2026-64284

In the Linux kernel, the following vulnerability has been resolved: KVM: x86: Ensure vendor's exit handler runs before fastpath userspace exits Move the handling of fastpath userspace exits into vendor code to ensure KVM runs vendor specific operations that need to run before userspace gains...

EUVD-2026-48992

In the Linux kernel, the following vulnerability has been resolved: fpga: dfl-afu: validate DMA mapping length in afudmamapregion afuioctldmamap accepts a 64-bit length from userspace via DFLFPGAPORTDMAMAP ioctl without an upper bound check. The value is passed to afudmapinpages where npages is...

EUVD-2026-48979

In the Linux kernel, the following vulnerability has been resolved: fuse: avoid 32-bit prune notification count wrap FUSENOTIFYPRUNE validates the nodeid payload length with: size - sizeofoutarg != outarg.count sizeofu64 On 32-bit kernels, sizet is also 32 bits, so the daemon-controlled count...

CVE-2026-64258 fuse-uring: remove request-less entries from ent_w_req_queue to fix NULL deref

In the Linux kernel, the following vulnerability has been resolved: fuse-uring: remove request-less entries from entwreqqueue to fix NULL deref If a copy into the userspace ring buffer fails, a request will be terminated and fuseuringreqend will set ent-fusereq to NULL but it will leave the entry...

CVE-2026-64259

CVE-2026-64259 (Linux kernel, fuse-uring) : A race allowed a use-after-free in fuse-uring by letting a fuse_req on an SQE commit become findable after memcpy, if a malicious userspace sent commit SQEs before the request reached fuse-server. The fix reorders operations: moving fuse_uring_add_to_pq...

PT-2026-64548

In the Linux kernel, the following vulnerability has been resolved: usb: gadget: f fs: Initialize epfile-in early to fix endpoint direction checks When parsing endpoint descriptors, ffs data got descs generates the eps addrmap which contains the endpoint direction. However, epfile-in was previous...

kernel: KVM: x86: Don't (re)check L1 intercepts when completing userspace I/O

In the Linux kernel, the following vulnerability has been resolved: KVM: x86: Don't recheck L1 intercepts when completing userspace I/O When completing emulation of instruction that generated a userspace exit for I/O, don't recheck L1 intercepts as KVM has already finished that phase of instructi...

EUVD-2026-48642

In the Linux kernel, the following vulnerability has been resolved: usb: gadget: uvc: hold opts-lock across XU walks in uvcfunctionbind uvcfunctionbind walks &opts-extensionunits twice without holding opts-lock: - directly, for the iExtension string-descriptor fixup loop; - indirectly, four times...

kernel: KVM: x86: Don't (re)check L1 intercepts when completing userspace I/O

In the Linux kernel, the following vulnerability has been resolved: KVM: x86: Don't recheck L1 intercepts when completing userspace I/O When completing emulation of instruction that generated a userspace exit for I/O, don't recheck L1 intercepts as KVM has already finished that phase of instructi...

kernel: KVM: x86: Don't (re)check L1 intercepts when completing userspace I/O

In the Linux kernel, the following vulnerability has been resolved: KVM: x86: Don't recheck L1 intercepts when completing userspace I/O When completing emulation of instruction that generated a userspace exit for I/O, don't recheck L1 intercepts as KVM has already finished that phase of instructi...