VulnerabilityPublished 18 Oct 2026

CVE-2026-98861: Linux kernel · fprobe: Use guard(rcu_sched_notrace) and check rcu_is_watching()

Source GCVE Database

Authoritative record:CVE-2026-98861· High

Not known to be exploited · fixed in e0a6249190402a28f1e2925a81acf573157d55ef : patch Linux kernel soon.

Data as of 26 Oct 2026, 17:16 UTC

Severity

High

Rated by Threat Radar · CVSS not yet scored by NVD

EPSS: 0.1% chance of exploitation in 30 days – higher than 5% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.
Patch: Available – fixed in e0a6249190402a28f1e2925a81acf573157d55ef, dd4a0d4993633b45470abf6da4ea0ca563402245, a85d0f00671b4d4527317c10ba018680f7d8d673 +2

Exploitation evidence

Disclosed: evidence found.
CVE published 18 Oct 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-7564-v46w-3pmr

What to do

Upgrade to a fixed release listed under Affected software.

Affected software

Product	Affected	Fixed in
LinuxLinux	Affected >=6.18.34 <6.18.56 >=7.0.11 <7.1	Fixed in e0a6249190402a28f1e2925a81acf573157d55ef dd4a0d4993633b45470abf6da4ea0ca563402245 a85d0f00671b4d4527317c10ba018680f7d8d673 7.1 6.18.56
LinuxLinux	Affected =7.1	Fixed in–

AI-suggested

A fix for this vulnerability has been implemented in the Linux kernel by introducing guard(rcu_sched_notrace) and checks for rcu_is_watching() in fprobe handlers to ensure safe synchronization and prevent use-after-free. Users should update to the fixed kernel versions once available.

Description

A use-after-free vulnerability in the Linux kernel's fprobe subsystem has been resolved. The issue arises because unregister_fprobe() and unregister_fprobe_async() rely on standard RCU grace periods that do not track execution when RCU is not watching, such as in idle or nohz_full states. This can lead to use-after-free if an fprobe handler runs during these states after unregistration. The fix involves using guard(rcu_sched_notrace) and checking rcu_is_watching() to ensure handlers exit early when RCU is not watching, and reducing lockdep overhead by replacing rcu_read_lock() with rcu_read_lock_sched_notrace() where appropriate.

References

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