In the Linux kernel, the following vulnerability has been resolved: iio: event: Fix event FIFO reset race `iio_event_getfd()` creates the event file descriptor with `anon_inode_getfd()`, which allocates a new fd, creates the anonymous file and installs it in the process fd table before returning to the caller. The IIO code resets the event FIFO after `anon_inode_getfd()` has returned, but before `IIO_GET_EVENT_FD_IOCTL` has copied the fd number to userspace. But since fd tables are shared between threads, another thread can guess the newly allocated fd number and issue a `read()` on it as soon as the fd has been installed. This means the `kfifo_to_user()` in `iio_event_chrdev_read()` can run in parallel with the `kfifo_reset_out()` in `iio_event_getfd()`. The kfifo documentation says that `kfifo_reset_out()` is only safe when it is called from the reader thread and there is only one concurrent reader. Otherwise it is dangerous and must be handled in the same way as `kfifo_reset()`. If that happens, `kfifo_to_user()` can advance the FIFO `out` index based on state from before the reset, after the reset has already moved the `out` index to the current `in` index. That can leave the FIFO with an `out` index past the `in` index. A later `read()` can then see an underflowed FIFO length and copy more data than the event FIFO buffer contains. This can result in an out-of-bounds read and leak adjacent kernel memory to userspace. Move the FIFO reset before `anon_inode_getfd()`. At that point the event fd is marked busy, but the new fd has not been installed yet, so userspace cannot access it while the FIFO is reset.

A flaw was found in the Linux kernel's Industrial I/O (IIO) event subsystem. A local user can exploit a race condition during the reset of the event FIFO (First-In, First-Out) buffer. This occurs when another thread accesses a newly allocated file descriptor before the FIFO reset is complete. This can lead to an out-of-bounds read, potentially disclosing sensitive kernel memory to the user.

Red Hat Enterprise Linux 8 2026-08-10T00:00:00Z RHSA-2026:52761 kernel-rt-0:4.18.0-553.154.1.rt7.495.el8_10 Red Hat Enterprise Linux 8 2026-08-10T00:00:00Z RHSA-2026:52765 kernel-0:4.18.0-553.154.1.el8_10 Red Hat Enterprise Linux 10 Affected kernel Red Hat Enterprise Linux 6 Not affected kernel Red Hat Enterprise Linux 7 Affected kernel Red Hat Enterprise Linux 7 Affected kernel-rt Red Hat Enterprise Linux 9 Affected kernel Red Hat Enterprise Linux 9 Affected kernel-rt Red Hat Hardened Images Not affected erlang27 https://www.cve.org/CVERecord?id=CVE-2026-64496 https://nvd.nist.gov/vuln/detail/CVE-2026-64496 https://lore.kernel.org/linux-cve-announce/2026072551-CVE-2026-64496-0a77@gregkh/T