VulnerabilityPublished 25 Jul 2026

CVE-2026-64496: Linux kernel · iio: event: Fix event FIFO reset race

Source GCVE Database

Authoritative record:CVE-2026-64496· High 7.1

Not known to be exploited · CVSS 7.1 High · fixed in f187dc5a4c4846ffa07d9bda6e760837ed005574 : patch Linux kernel soon.

Data as of 26 Oct 2026, 14:05 UTC

CVSS 3.1 base score

7.1High

How severe the flaw is on the 0–10 CVSS scale.

EPSS: 0.1% chance of exploitation in 30 days – higher than 2% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.
Patch: Available – fixed in f187dc5a4c4846ffa07d9bda6e760837ed005574, d16a702ca7d29c0b7a9b509339d1b044a1cadb32, af791d295737ea6b6ff2c8d8488462a49c14af01 +5

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

Attack Vector: Local
Attack Complexity: Low
Privileges Required: Low
User Interaction: None
Scope: Unchanged
Confidentiality: High
Integrity: None
Availability: High

Bold values are the worst case: easiest to exploit or largest impact.

Attack Vector: Local: The vulnerable component is not bound to the network stack and the attacker’s path is via read/write/execute capabilities. Either: the attacker exploits the vulnerability by accessing the target system locally (e.g., keyboard, console), or remotely (e.g., SSH); or the attacker relies on User Interaction by another person to perform actions required to exploit the vulnerability (e.g., tricking a legitimate user into opening a malicious document).
Attack Complexity: Low: Specialized access conditions or extenuating circumstances do not exist. An attacker can expect repeatable success against the vulnerable component.
Privileges Required: Low: The attacker is authorized with (i.e., requires) privileges that provide basic user capabilities that could normally affect only settings and files owned by a user. Alternatively, an attacker with Low privileges may have the ability to cause an impact only to non-sensitive resources.
User Interaction: None: The vulnerable system can be exploited without any interaction from any user.
Scope: Unchanged: An exploited vulnerability can only affect resources managed by the same security authority. In this case, the vulnerable component and the impacted component are either the same, or both are managed by the same security authority.
Confidentiality: High: There is total loss of confidentiality, resulting in all resources within the impacted component being divulged to the attacker. Alternatively, access to only some restricted information is obtained, but the disclosed information presents a direct, serious impact.
Integrity: None: There is no loss of integrity within the impacted component.
Availability: High: There is total loss of availability, resulting in the attacker being able to fully deny access to resources in the impacted component; this loss is either sustained (while the attacker continues to deliver the attack) or persistent (the condition persists even after the attack has completed). Alternatively, the attacker has the ability to deny some availability, but the loss of availability presents a direct, serious consequence to the impacted component (e.g., the attacker cannot disrupt existing connections, but can prevent new connections; the attacker can repeatedly exploit a vulnerability that, in each instance of a successful attack, leaks a only small amount of memory, but after repeated exploitation causes a service to become completely unavailable).

Definitions: FIRST CVSS v3.1 specification.

Exploitation evidence

Disclosed: evidence found.
CVE published 25 Jul 2026
Detectable: no evidence on record.
No public nuclei template indexed
Weaponised: no evidence on record.
No public exploit code indexed in Metasploit or Exploit-DB
Exploited in the wildExploited: no evidence on record.
Not in CISA KEV and no source reports exploitation
Observed by OffSeq MirageSeen by Mirage: no evidence on record.
No attack traffic recorded by OffSeq Mirage sensors

A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), the Metasploit, Exploit-DB and nuclei-templates index as of 26 Oct 2026.

Disclosed: The CVE record is public on cve.org. Its publication is t = 0.
Detectable: A public nuclei template can find exposed instances, for defenders and attackers alike.
Weaponised: Public exploit code exists in Metasploit or Exploit-DB, or CISA SSVC or the CVSS exploit maturity reports a public proof of concept.
Exploited in the wild: CISA KEV lists it, CISA SSVC rates exploitation active, or a source reports attacks.
Observed by OffSeq Mirage: OffSeq Mirage honeypot sensors recorded attack traffic for this CVE, or found exposed hosts without attack traffic.

Moments are spaced evenly, not to scale; a dashed line marks a gap of six months or more. Deltas count from t = 0. Sources that give only a date (CISA KEV, Exploit-DB, or a time of exactly 00:00Z) read “same day” rather than hours. Metasploit modules carry the flaw’s disclosure date, not their release date, and nuclei templates carry no date, so both appear above but not on the timeline.

ghsa-hh3r-jgc6-qr6q

What to do

Upgrade to a fixed release listed under Affected software.

Affected software

Product	Affected	Fixed in
LinuxLinux	Affected ≥ b91accafbb1031b80d22ad83576877ff2f8b4774, < f187dc5a4c4846ffa07d9bda6e760837ed005574	Fixed in f187dc5a4c4846ffa07d9bda6e760837ed005574
LinuxLinux	Affected ≥ b91accafbb1031b80d22ad83576877ff2f8b4774, < d16a702ca7d29c0b7a9b509339d1b044a1cadb32	Fixed in d16a702ca7d29c0b7a9b509339d1b044a1cadb32
LinuxLinux	Affected ≥ b91accafbb1031b80d22ad83576877ff2f8b4774, < af791d295737ea6b6ff2c8d8488462a49c14af01	Fixed in af791d295737ea6b6ff2c8d8488462a49c14af01
LinuxLinux	Affected ≥ b91accafbb1031b80d22ad83576877ff2f8b4774, < a13ef1adbc62085b21b546b07b0be7e2fbf52150	Fixed in a13ef1adbc62085b21b546b07b0be7e2fbf52150
LinuxLinux	Affected ≥ b91accafbb1031b80d22ad83576877ff2f8b4774, < 72c6aa8e0d74eab91b8694cde97dec088c248fee	Fixed in 72c6aa8e0d74eab91b8694cde97dec088c248fee
LinuxLinux	Affected ≥ b91accafbb1031b80d22ad83576877ff2f8b4774, < 9edefd4c56bee3fe331e0355d1f10a533134999d	Fixed in 9edefd4c56bee3fe331e0355d1f10a533134999d

AI-suggested

A fix has been implemented that moves the FIFO reset to occur before the event file descriptor is created and installed, preventing concurrent unsafe access. Since the vulnerability has been resolved in the Linux kernel source, users should update to a kernel version that includes this fix. Patch status is not explicitly stated in the input data; therefore, check the official Linux kernel advisories or distribution security updates for the fixed version and apply the update accordingly.

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.

Impact

An attacker with the ability to access the IIO event file descriptor concurrently from multiple threads could exploit this race condition to cause an out-of-bounds read from kernel memory. This could lead to leakage of sensitive kernel memory contents to userspace, potentially exposing sensitive information. There is no indication of known exploits in the wild. The vulnerability affects kernel memory confidentiality but does not describe privilege escalation or denial of service.

Summary

The vulnerability in the Linux kernel's IIO event subsystem involves a race condition between resetting the event FIFO and the installation of the event file descriptor in the process file descriptor table. The function iio_event_getfd() creates the event file descriptor with anon_inode_getfd(), which installs the fd before returning. The FIFO reset was previously done after this, allowing another thread to guess and read from the new fd concurrently. This leads to unsafe concurrent access to the FIFO, violating kfifo's concurrency requirements and potentially causing the FIFO 'out' index to advance incorrectly. This results in an out-of-bounds read that can leak kernel memory to userspace. The patch moves the FIFO reset before anon_inode_getfd(), ensuring the fd is not accessible during reset and eliminating the race.

References

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