VulnerabilityPublished 18 Oct 2026

CVE-2026-98613: Linux kernel · bpf: Bound ownership depth through local kptrs and graph roots

Affects Linux kernelSource CVE Database V5

Not known to be exploited · fixed in bfc888f04588f591851e95c974954cfca58e6c19 : patch Linux kernel soon.

Data as of 26 Oct 2026, 17:16 UTC

Severity

High

Rated High by Threat Radar's AI analysis · CVSS not yet scored by NVD

EPSS: 0.1% chance of exploitation in 30 days – higher than 7% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.
Patch: Available – fixed in bfc888f04588f591851e95c974954cfca58e6c19, 4105870a4b8afe852aeb24a6dd58e1836cc4ce58, 92aa0502c781d72bb9685245c3280efb3766a110 +1

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.

What to do

Upgrade Linux kernel to bfc888f04588f591851e95c974954cfca58e6c19, 4105870a4b8afe852aeb24a6dd58e1836cc4ce58, 92aa0502c781d72bb9685245c3280efb3766a110 or 9c11e543fec32e92b3aa3f693339ca3ee79ea9dd.

Affected software

Product	Affected	Fixed in
LinuxLinux	Affected ≥ b0966c724584a5a9fd7fb529de19807c31f27a45, < bfc888f04588f591851e95c974954cfca58e6c19	Fixed in bfc888f04588f591851e95c974954cfca58e6c19
LinuxLinux	Affected ≥ b0966c724584a5a9fd7fb529de19807c31f27a45, < 4105870a4b8afe852aeb24a6dd58e1836cc4ce58	Fixed in 4105870a4b8afe852aeb24a6dd58e1836cc4ce58
LinuxLinux	Affected ≥ b0966c724584a5a9fd7fb529de19807c31f27a45, < 92aa0502c781d72bb9685245c3280efb3766a110	Fixed in 92aa0502c781d72bb9685245c3280efb3766a110
LinuxLinux	Affected ≥ b0966c724584a5a9fd7fb529de19807c31f27a45, < 9c11e543fec32e92b3aa3f693339ca3ee79ea9dd	Fixed in 9c11e543fec32e92b3aa3f693339ca3ee79ea9dd
LinuxLinux	Affected =6.12	Fixed in–

AI-suggested

A fix for this vulnerability is available and included in Linux kernel version 6.12 and subsequent commits identified by the fixedVersions hashes. Users and administrators should upgrade to Linux kernel 6.12 or later to mitigate this issue. No additional mitigation steps are required as the vulnerability is addressed by bounding ownership depth and improving validation in the kernel's BPF code.

Description

A vulnerability in the Linux kernel's BPF subsystem allows program-allocated objects to create arbitrarily deep ownership chains through local kernel pointers (kptrs). This can lead to kernel stack exhaustion when dropping the head of such chains. The issue arises from insufficient bounding of ownership depth in bpf_obj_free_fields() and btf_check_and_fixup_fields(), which has been addressed by imposing a maximum depth limit and improved validation of ownership relationships.

Impact

Exploitation of this vulnerability can cause kernel stack exhaustion due to unbounded recursive destruction of deeply nested or cyclic program-allocated objects in the BPF subsystem. This may lead to denial of service (kernel crash or instability). There is no indication of privilege escalation or code execution impact. No known exploits in the wild have been reported.

Summary

CVE-2026-98613 affects the Linux kernel's BPF (Berkeley Packet Filter) implementation. Program-allocated objects can own other local objects via referenced local kptrs, forming deep or cyclic ownership chains. The function bpf_obj_free_fields() recursively drops these objects synchronously before freeing storage, which can exhaust the kernel stack if the chain is too deep. The vulnerability stems from btf_check_and_fixup_fields() assuming ownership only through graph roots and nodes, missing local kptr edges introduced by bpf_kptr_xchg(). The fix replaces the old ownership restriction with a bounded ownership walk that rejects cycles and paths deeper than eight record-bearing types, preventing stack exhaustion during recursive destruction. This fix is included in Linux kernel version 6.12 and later.

References

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Exploitation evidence

What to do

Affected software

Description

AI analysisMachine-generated, updated 26 Oct 2026, 10:09 UTC

Technical details

References

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