Strix
26.1K

CVE-2026-64496

HIGHCVSS 7.1/10EPSS 0.18%

Last modified

CVE-2026-64496 is a high-severity vulnerability rated 7.1/10 on the CVSS scale. 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. EPSS estimates a 0.18% chance of exploitation in the next 30 days.

Description

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.

Metrics

CVSS 3.1
7.1/10

CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:H

EPSS Probability
0.18%

7.5th percentile

Probability of exploitation in the next 30 days. Learn more

Affected Software

Source: CNA advisory (CVE.org). NVD analysis pending.

VendorProductVersions
LinuxLinux>= b91accafbb1031b80d22ad83576877ff2f8b4774, < 9dc84ba4be5bbeb29ee49efe6cea2cb32c461424; >= b91accafbb1031b80d22ad83576877ff2f8b4774, < d16a702ca7d29c0b7a9b509339d1b044a1cadb32; >= b91accafbb1031b80d22ad83576877ff2f8b4774, < a13ef1adbc62085b21b546b07b0be7e2fbf52150; >= b91accafbb1031b80d22ad83576877ff2f8b4774, < 0d4a646d7f87ea3625fafe387043fddc6a2f5e7f; >= b91accafbb1031b80d22ad83576877ff2f8b4774, < 72c6aa8e0d74eab91b8694cde97dec088c248fee; >= b91accafbb1031b80d22ad83576877ff2f8b4774, < 9edefd4c56bee3fe331e0355d1f10a533134999d; >= b91accafbb1031b80d22ad83576877ff2f8b4774, < f187dc5a4c4846ffa07d9bda6e760837ed005574; >= b91accafbb1031b80d22ad83576877ff2f8b4774, < af791d295737ea6b6ff2c8d8488462a49c14af01
LinuxLinux3.15

References

Timeline

Published
Last Modified
Status
Received

Frequently Asked Questions

What is CVE-2026-64496?
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.
How severe is CVE-2026-64496?
CVE-2026-64496 has a CVSS score of 7.1/10 (HIGH severity). The EPSS model estimates a 0.18% probability of exploitation in the next 30 days.
How do I fix CVE-2026-64496?
Check the vendor references and advisories linked above for patched versions and mitigation guidance. You can also run a Strix scan to test if your systems are affected.

How Strix Helps

Related CVEs from 2026

View all 2026CVEs →

Are you affected by CVE-2026-64496?

Run a free Strix scan to check your systems for this vulnerability.

Scan your code now

Source: NVD / NIST