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CVE.org (no NVD analysis yet)· CNA Linux

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

—No exploit Fix available

Noroxi assessment

Priority: Monitor (action score 0/100)

  • The sources we track (CISA KEV, Exploit-DB, Metasploit, Nuclei, GitHub) show no public exploit code or exploitation in the wild.
  • Probability of exploitation in the next 30 days: 0.16% (FIRST EPSS).
  • Fixed version: Linux Linux 6.18.56, 7.1, a85d0f00671b4d4527317c10ba018680f7d8d673.

Low priority for now. Upgrade to Linux Linux 6.18.56, 7.1, a85d0f00671b4d4527317c10ba018680f7d8d673 or later.

Generated automatically from the record's data: CVSS (NVD and CNA), CISA KEV and SSVC, FIRST EPSS, exploit sources, fixed versions. How we calculate it

Primary sources: NVD · CVE.org · FIRST EPSS

In the Linux kernel, the following vulnerability has been resolved: fprobe: Use guard(rcu_sched_notrace) and check rcu_is_watching() unregister_fprobe() and unregister_fprobe_async() (used by BPF kprobe-multi) rely on standard RCU grace periods (synchronize_rcu() and call_rcu()) to wait until in-flight fprobe handlers complete before freeing the fprobe. However, if an fprobe handler executes while RCU is not watching (such as in the idle loop or nohz_full extended quiescent states), standard RCU does not track preemption-disabled sections. Consequently, synchronize_rcu() does not wait for those executions, which can lead to a use-after-free if the fprobe is freed immediately after unregistration. Ensure handlers exit early when !rcu_is_watching(). Furthermore, fprobe_fgraph_entry() and fprobe_ftrace_entry() previously used guard(rcu)() and rcu_read_lock(), which invoke lockdep on every hit under CONFIG_PROVE_LOCKING. This adds overhead and can cause lockdep recursion if probed functions interact with lockdep. Since rhltable_lookup() and rhl_for_each_entry_rcu() use rcu_dereference_all_check() (which checks rcu_read_lock_any_held()), holding preemption disabled via rcu_read_lock_sched_notrace() is fully valid and sufficient so long as rcu_is_watching() is true. Define and use guard(rcu_sched_notrace)() across fprobe_ftrace_entry(), fprobe_fgraph_entry(), and fprobe_return(). This eliminates fast-path rcu_read_lock() and lockdep overhead while guaranteeing safe grace period synchronization.

Published
Oct 18, 2026
Updated
Oct 19, 2026
EPSS
0.1% · 6th percentile
CWE
—

Report tools

JSON

Action score

0

Monitor

Low priority for now.

CVSS
0 / 40 · —
CISA KEV
0 / 30 · Not listed
EPSS
0 / 30 · 0.1%

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Noroxi analysis

What does it mean in your environment?

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Affected systems

Is your version affected?

Pick the product and type the version you run. It's compared with this record's version ranges in your browser; the version isn't sent anywhere.

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Versions reported by the vendor

Affected version ranges reported by the assigning authority (Linux). Independent of NVD's CPE analysis and usually ahead of it.

  • Linux Linux

    • a4f6a9005ed6cfd360ef2520430927f05f92ffb0, 7.1affected
    • 56b4cfcf1518245493c60fd39c56978f508f1816 and later · before a85d0f00671b4d4527317c10ba018680f7d8d673affected · git
    • 657b594b2084b39a4bc6d8493aa2140cb00cea49 and later · before dd4a0d4993633b45470abf6da4ea0ca563402245affected · git
    • 657b594b2084b39a4bc6d8493aa2140cb00cea49 and later · before e0a6249190402a28f1e2925a81acf573157d55efaffected · git
    • 6.18.34 and later · before 6.18.56affected · semver
    • 7.0.11 and later · before 7.1affected · semver
    • before 7.1not affected · semver
    • 6.18.56 and later · up to and including 6.18.*not affected · semver
    • 7.2.10 and later · up to and including 7.2.*not affected · semver
    • 7.3 and laternot affected · original_commit_for_fix

Package-level exposure

OSV and GitHub Advisory data: ecosystem, package and range. SBOM matching uses this table.

EcosystemPackageAffected rangeFix
Debian:14linuxbefore 7.2.10-17.2.10-1

Same product

linux: all records

Other highest-scoring records for the same primary product.

  • CVE-2026-74705udp: fix potential use-after-free in tunnel segmentation
    40Plan
  • CVE-2026-74612veth: fix skb length accounting after XDP frag adjustment
    40Plan
  • CVE-2026-74475vxlan: use neigh_ha_snapshot() in route_shortcircuit()
    40Plan

Published before and after this one in the same product

  • ← EarlierCVE-2026-98859Oct 18, 2026 · HID: multitouch: stop the release timer from being rearmed on remove
    0Monitor
  • ← EarlierCVE-2026-98860Oct 18, 2026 · HID: bpf: cast size to ssize_t when checking hid_bpf_hw_request
    0Monitor
  • Later →CVE-2026-98862Oct 18, 2026 · audit: fix exe mark UAF in kill_rules()
    0Monitor

Remediation

Which version to upgrade to

Fix versions compiled from the vendor, package registries and Microsoft. Verify the vendor's note before upgrading.

Product / packageFixed versionSource
Linux Linux6.18.56Vendor (CNA)
Linux Linux7.1Vendor (CNA)
Linux Linuxa85d0f00671b4d4527317c10ba018680f7d8d673Vendor (CNA)
Linux Linuxdd4a0d4993633b45470abf6da4ea0ca563402245Vendor (CNA)
Linux Linuxe0a6249190402a28f1e2925a81acf573157d55efVendor (CNA)
debian:linux7.2.10-1 · Debian:14Package registry (OSV)

Exploit status

No known public exploit

No public exploit has been observed yet. That doesn't mean you're safe, only that the bar is a little higher.

Research context

For pentesters and researchers: attack profile, score disagreement, timeline, patch commits, credits, variant and chain candidates, bug bounty scope. All derived from existing data; no exploit code.

Timeline

From publication to today: proof of concept, Metasploit module, CISA KEV and fix record. Dates are as reported by the sources.

  1. Published
  2. Fix recordedsame day
  3. TodayNov 12, 2026+25 d
EPSS, last 120 days

FIRST EPSS daily score; only changes of 0.01 or more are recorded (step chart).

Not on record for this CVE: patch commit or PR link · researcher credit · variant or chain candidate · public bounty program.

Technical details

No CVSS vector for this record, so attack conditions can't be derived.

Weakness class (CWE)

—

Attack context

MITRE CAPEC attack patterns and ATT&CK techniques for this weakness class (CWE). A starting point for detection rules and threat hunting.

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References

Show all references (2 more)

Vendor advisories and official records. Exploit/PoC links are deliberately left out.

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