VulnerabilityPublished 19 Jul 2026

CVE-2026-64075: Linux kernel · fprobe: Fix unregister_fprobe() to wait for RCU grace period

Source GCVE Database

Not known to be exploited · CVSS 7.8 High.

Data as of 26 Oct 2026, 15:59 UTC

CVSS 3.1 base score

7.8High

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

EPSS: 0.1% chance of exploitation in 30 days – higher than 6% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.

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

Attack Vector: Local
Attack Complexity: Low
Privileges Required: Low
User Interaction: None
Scope: Unchanged
Confidentiality: High
Integrity: High
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: High: There is a total loss of integrity, or a complete loss of protection. For example, the attacker is able to modify any/all files protected by the impacted component. Alternatively, only some files can be modified, but malicious modification would present a direct, serious consequence to 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 19 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-q3rx-6vfg-rc7w

What to do

AI-suggested

A fix is available in the Linux kernel that adds synchronize_rcu() in unregister_fprobe() to wait for the RCU grace period. Users should update to a kernel version that includes this fix. For BPF users, the asynchronous unregister_fprobe_async() function is introduced and used to avoid this issue. Patch status is not explicitly stated in the input; therefore, check the vendor advisory or Linux kernel release notes for the exact fixed versions and apply updates accordingly.

Description

A use-after-free vulnerability in the Linux kernel's fprobe component was fixed by ensuring unregister_fprobe() waits for the RCU grace period. The issue arose because fprobe registration to an rcu-hlist did not properly wait for RCU synchronization, potentially causing use-after-free if fprobe was released immediately after unregistering. The fix adds synchronize_rcu() in unregister_fprobe() to prevent this. BPF-related code paths are not affected due to different deallocation mechanisms.

Impact

The vulnerability could cause use-after-free conditions in the Linux kernel's fprobe code, potentially leading to kernel memory corruption or crashes when fprobe is released immediately after unregistering. However, BPF-related code paths are not impacted due to different deallocation methods. No known exploits in the wild have been reported.

Summary

The Linux kernel's fprobe functionality was modified in commit 4346ba1604093 to register fprobe structures to an RCU-protected list but failed to wait for the RCU grace period during unregister_fprobe(). This omission could lead to a use-after-free condition if the fprobe was released immediately after unregistering, affecting fprobe event and sample module code. The vulnerability was addressed by adding synchronize_rcu() in unregister_fprobe() to ensure proper waiting for the RCU grace period before freeing. BPF usage of fprobe is unaffected because it unregisters and deallocates fprobe asynchronously via RCU callbacks. An asynchronous unregister function, unregister_fprobe_async(), was also introduced for BPF use cases.

References

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