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Fencer Vulns
high 7.1

CVE-2026-64496 json

iio: event: Fix event FIFO reset race

published 2026-07-25 3 mo ago modified 2026-11-03 5 d ago also EUVD-2026-48840

cvss
7.1
version 3.1, CNA
cisa kev
Not listed
not in CISA's catalog
epss
0.1%
EPSS 0.1% chance of exploitation in 30 days, percentile 2%
public exploits
0
none known

Summary

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.

Patch / fix

  • Linux Linux 5.10.261, 5.15.212, 6.1.178, 6.6.145, 6.12.96, 6.18.39, 7.1.4, 7.2
  • linux Debian 12 6.1.180-1
  • linux Debian 13 6.12.96-1
  • linux Debian 14 7.1.4-1
  • linux-6.12 Debian 12 6.12.100-1~deb12u1

debian advisories DEBIAN-CVE-2026-64496

  • linux Ubuntu 22.04 LTS 5.15.0-198.208
  • linux Ubuntu 24.04 LTS 6.8.0-147.147
  • linux Ubuntu 26.04 LTS 7.0.0-31.31
  • linux-aws Ubuntu 22.04 LTS 5.15.0-1117.124
  • linux-aws Ubuntu 24.04 LTS 6.8.0-1067.70
  • linux-aws Ubuntu 26.04 LTS 7.0.0-1012.12
  • linux-gcp Ubuntu 22.04 LTS 5.15.0-1118.128
  • linux-gcp Ubuntu 24.04 LTS 6.8.0-1071.79

ubuntu advisories UBUNTU-CVE-2026-64496

Ubuntu security data © Canonical Ltd., from https://github.com/canonical/ubuntu-security-notices via OSV; changed: normalised to fixed package versions per release. CC BY-SA 4.0

  • kernel RHEL 8 4.18.0-553.154.1.el8_10
  • perf RHEL 8 4.18.0-553.154.1.el8_10
  • bpftool RHEL 8 4.18.0-553.154.1.el8_10
  • kernel-core RHEL 8 4.18.0-553.154.1.el8_10
  • kernel-tools RHEL 8 4.18.0-553.154.1.el8_10
  • python3-perf RHEL 8 4.18.0-553.154.1.el8_10
  • kernel-modules RHEL 8 4.18.0-553.154.1.el8_10
  • kernel-zfcpdump RHEL 8 4.18.0-553.154.1.el8_10

red hat advisories RHSA-2026:52765RHSA-2026:52761

  • kernel-64kb SLE Module for Basesystem 15 SP7 6.4.0-150700.53.81.1
  • kernel-syms SLE Module for Development Tools 15 SP7 6.4.0-150700.53.81.1
  • kernel-azure SLE Module for Public Cloud 15 SP7 6.4.0-150700.53.81.1
  • kernel-source SLE Module for Development Tools 15 SP7, SLE Module for Basesystem 15 SP7 6.4.0-150700.53.81.1
  • kernel-default SLE Workstation Extension 15 SP7, SLE Module for Legacy 15 SP7, SLE Module for Basesystem 15 SP7 +2 more 6.4.0-150700.53.81.1
  • kernel-zfcpdump SLE Module for Basesystem 15 SP7 6.4.0-150700.53.81.1
  • kernel-obs-build SLE Module for Development Tools 15 SP7 6.4.0-150700.53.81.1
  • kernel-default-base SLE Module for Basesystem 15 SP7 6.4.0-150700.53.81.1.150700.17.45.1

suse advisories SUSE-SU-2026:4687-1SUSE-SU-2026:4254-1SUSE-SU-2026:23887-1SUSE-SU-2026:23902-1SUSE-SU-2026:23897-1SUSE-SU-2026:23881-1

  • kernel-rt openSUSE Leap 16.0 6.12.0-160000.38.1
  • dtb-aarch64 openSUSE Leap 16.0 6.12.0-160000.38.1
  • kernel-64kb openSUSE Leap 16.0 6.12.0-160000.38.1
  • kernel-syms openSUSE Leap 16.0 6.12.0-160000.38.1
  • kernel-azure openSUSE Leap 16.0 6.12.0-160000.38.1
  • kernel-obs-qa openSUSE Leap 16.0 6.12.0-160000.38.1
  • kernel-source openSUSE Leap 16.0 6.12.0-160000.38.1
  • kernel-default openSUSE Leap 16.0 6.12.0-160000.38.1

opensuse advisories openSUSE-SU-2026:21910-1openSUSE-SU-2026:11476-1

  • kernel-rt AlmaLinux 8 4.18.0-553.154.1.rt7.495.el8_10
  • kernel-rt-core AlmaLinux 8 4.18.0-553.154.1.rt7.495.el8_10
  • kernel-rt-modules AlmaLinux 8 4.18.0-553.154.1.rt7.495.el8_10
  • kernel-rt-debug-core AlmaLinux 8 4.18.0-553.154.1.rt7.495.el8_10
  • kernel-rt-debug-modules AlmaLinux 8 4.18.0-553.154.1.rt7.495.el8_10
  • kernel-rt-modules-extra AlmaLinux 8 4.18.0-553.154.1.rt7.495.el8_10
  • kernel-rt-debug-modules-extra AlmaLinux 8 4.18.0-553.154.1.rt7.495.el8_10
  • kernel AlmaLinux 8 4.18.0-553.154.1.el8_10

almalinux advisories ALSA-2026:52761ALSA-2026:52765

  • kernel-rt Rocky Linux 8 4.18.0-553.154.1.rt7.495.el8_10
  • kernel Rocky Linux 8 4.18.0-553.154.1.el8_10

rocky linux advisories RLSA-2026:52761RLSA-2026:52765

  • kernel Azure Linux 3.0 6.6.145.2-1

azure linux advisories AZL-93731

Azure Linux vulnerability data, Copyright (c) Microsoft Corporation, from https://github.com/microsoft/AzureLinuxVulnerabilityData via OSV, under the MIT licence; changed: normalised to fixed package versions per release. MIT

Vendor advisories

What the vendors themselves say about their products: affected, fixed or not affected, and what to do.

red hat product security vex CVE-2026-64496 updated cvss 5.5

kernel: iio: event: Fix event FIFO reset race

  • Red Hat Enterprise Linux 7 perf, kernel, bpftool, kernel-rt, python-perf, kernel-kdump, +9 more Red Hat Enterprise Linux 9 rv, perf, rtla, kernel, bpftool, libperf, +84 more
    affected: workaround, no fix available, no fix planned “Will not fix”
  • Red Hat Enterprise Linux 10 kernel 6.12.0-250.el10
    affected: workaround, no fix planned “Will not fix”
  • Red Hat Enterprise Linux BaseOS (v. 8) perf 4.18.0-553.154.1.el8_10, kernel 4.18.0-553.154.1.el8_10, bpftool 4.18.0-553.154.1.el8_10, kernel-core 4.18.0-553.154.1.el8_10, kernel-tools 4.18.0-553.154.1.el8_10, python3-perf 4.18.0-553.154.1.el8_10, +15 more Red Hat Enterprise Linux CRB (v. 8) kernel-debuginfo-common-x86_64 4.18.0-553.154.1.el8_10, kernel-debuginfo-common-aarch64 4.18.0-553.154.1.el8_10, kernel-debuginfo-common-ppc64le 4.18.0-553.154.1.el8_10
    fixed: vendor fix RHSA-2026:52765
  • Red Hat Enterprise Linux NFV (v. 8) kernel-rt 4.18.0-553.154.1.rt7.495.el8_10, kernel-rt-kvm 4.18.0-553.154.1.rt7.495.el8_10, kernel-rt-core 4.18.0-553.154.1.rt7.495.el8_10, kernel-rt-modules 4.18.0-553.154.1.rt7.495.el8_10, kernel-rt-debug-kvm 4.18.0-553.154.1.rt7.495.el8_10, kernel-rt-debug-core 4.18.0-553.154.1.rt7.495.el8_10, +4 more Red Hat Enterprise Linux RT (v. 8) kernel-rt 4.18.0-553.154.1.rt7.495.el8_10, kernel-rt-core 4.18.0-553.154.1.rt7.495.el8_10, kernel-rt-modules 4.18.0-553.154.1.rt7.495.el8_10, kernel-rt-debug-core 4.18.0-553.154.1.rt7.495.el8_10, kernel-rt-debug-modules 4.18.0-553.154.1.rt7.495.el8_10, kernel-rt-modules-extra 4.18.0-553.154.1.rt7.495.el8_10, +2 more
    fixed: vendor fix RHSA-2026:52761
  • Red Hat Enterprise Linux 6 perf, kernel, python-perf, kernel-kdump, kernel-firmware, kernel-bootwrapper, +2 more
    not affected: vulnerable code not present

Red Hat CSAF VEX © Red Hat, Inc., from https://security.access.redhat.com/data/csaf/v2/vex/; changed: reduced to product statuses and remediations. CC BY 4.0 · csaf

CISA SSVC

Exploitation
none
Automatable
no
Technical impact
partial
Assessed
23 d ago

Exploit prediction

0.12% chance of exploitation in the next 30 days, higher than 2% of all scored CVEs (FIRST EPSS, 2026-11-08).

CVSS scores

assigned by version score vector
CNA 3.1 7.1 CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:H

Affected products

  • Linux Linux

Classification

Weakness
  • CWE-362 Concurrent Execution using Shared Resource with Improper Synchronization
Technology feeds

References

Sources

Fencer Vulns keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.