CVE-2024-40909

Kernel compromise via stale BPF deallocator call

Published Jul 12, 2024 · Updated Aug 5, 2026

Use-after-free in Linux 6.6.26 through 6.6.34 and 6.8.5 through 6.9.5 allows local users to compromise the kernel via BPF links. bpf_link_free follows dealloc_deferred after it can free the link, then reads link->ops->dealloc from that freed object and can call through recycled memory. Reaching the path requires BPF and performance-monitoring privileges; successful reuse grants kernel memory access and control-flow hijacking, while an unweaponized trigger can panic the kernel.

CVSS severity7.8
High
EPSS probability0.28%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Use-after-free in Linux 6.6.26 through 6.6.34 and 6.8.5 through 6.9.5 allows local users to compromise the kernel via BPF links. bpf_link_free follows dealloc_deferred after it can free the link, then reads link->ops->dealloc from that freed object and can call through recycled memory. Reaching the path requires BPF and performance-monitoring privileges; successful reuse grants kernel memory access and control-flow hijacking, while an unweaponized trigger can panic the kernel.

The record

CVE
CVE-2024-40909
Published
Jul 12, 2024
Updated
Aug 5, 2026
Vendor
The Linux Kernel Organization
Product
Linux
Classifications
T1068
Attack vector
local
Privileges
authenticated

Timeline

How it unfolded

  1. Jul 12, 2024CVE publishedPublication date reported by the CVE source.
  2. Aug 5, 2026Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=1a80dbcb2dbaf6e4c216e62e30fa7d3daa8001ce <2884dc7d08d98a89d8d65121524bb7533183a63a
  2. Affected versionversion=1a80dbcb2dbaf6e4c216e62e30fa7d3daa8001ce <fa97b8fed9896f1e89cb657513e483a152d4c382
  3. Affected versionversion=5d8d447777564b35f67000e7838e7ccb64d525c8
  4. Affected versionversion=6.6.26 <6.6.35
  5. Affected versionversion=6.8.5 <6.9
  6. Affected versionversion=6.9
  7. Affected versionversion=876941f533e7b47fc69977fc4551c02f2d18af97 <91cff53136daeff50816b0baeafd38a6976f6209

What conditions does exploitation require?

Attack vectorlocal
Required privilegesauthenticated

What is affected?

The Linux Kernel Organization · Linuxversion=1a80dbcb2dbaf6e4c216e62e30fa7d3daa8001ce <2884dc7d08d98a89d8d65121524bb7533183a63a; version=1a80dbcb2dbaf6e4c216e62e30fa7d3daa8001ce <fa97b8fed9896f1e89cb657513e483a152d4c382; version=5d8d447777564b35f67000e7838e7ccb64d525c8; version=6.6.26 <6.6.35; version=6.8.5 <6.9; version=6.9; version=876941f533e7b47fc69977fc4551c02f2d18af97 <91cff53136daeff50816b0baeafd38a6976f6209

Published CVSS scores

7.8Linux CNACVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

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No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectorlocal
Privilegesauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

T1068Exploitation for Privilege Escalation

Public exploit references

No public exploit references are available in this record.

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Technologies

Your stack

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Your stack

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