CVE-2026-72137Public exploit

Local privilege escalation via post-handoff skb free

Published Aug 15, 2026 · Updated Aug 15, 2026

A double free in the Linux kernel xfrm NAT-keepalive path allows local users to gain elevated privileges through memory corruption. nat_keepalive_send() frees an skb after ip_build_and_send_pkt() or ip6_xmit() has taken ownership and may already have consumed it. Exploitation requires local access to an affected kernel and reachability of the xfrm NAT-keepalive send path; successful exploitation can elevate privileges, while failed attempts can crash the kernel.

CVSS severity9.8
Critical
EPSS probability0.66%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

A double free in the Linux kernel xfrm NAT-keepalive path allows local users to gain elevated privileges through memory corruption. nat_keepalive_send() frees an skb after ip_build_and_send_pkt() or ip6_xmit() has taken ownership and may already have consumed it. Exploitation requires local access to an affected kernel and reachability of the xfrm NAT-keepalive send path; successful exploitation can elevate privileges, while failed attempts can crash the kernel.

The record

CVE
CVE-2026-72137
Published
Aug 15, 2026
Updated
Aug 15, 2026
Vendor
The Linux Kernel Organization
Product
Linux
Classifications
CWE-1341, T1068
Attack vector
local
Privileges
authenticated

Timeline

How it unfolded

  1. Aug 15, 2026CVE publishedPublication date reported by the CVE source.
  2. Aug 15, 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=6.11
  2. Affected versionversion=f531d13bdfe3f4f084aaa8acae2cb0f02295f5ae <226f4a490d1a938fc838d8f8c46a4eca864c0d78
  3. Affected versionversion=f531d13bdfe3f4f084aaa8acae2cb0f02295f5ae <5b0c4c916f202b8fd13d12afb6af62b385622f81
  4. Affected versionversion=f531d13bdfe3f4f084aaa8acae2cb0f02295f5ae <a8a7e6a9ff8a4c1f067694ddbd44be67fdf36693
  5. Affected versionversion=f531d13bdfe3f4f084aaa8acae2cb0f02295f5ae <d0a4dc7efa825bce60a8da8f7d43c864a159abde

What conditions does exploitation require?

Attack vectorlocal
Required privilegesauthenticated

What is affected?

The Linux Kernel Organization · Linuxversion=6.11; version=f531d13bdfe3f4f084aaa8acae2cb0f02295f5ae <226f4a490d1a938fc838d8f8c46a4eca864c0d78; version=f531d13bdfe3f4f084aaa8acae2cb0f02295f5ae <5b0c4c916f202b8fd13d12afb6af62b385622f81; version=f531d13bdfe3f4f084aaa8acae2cb0f02295f5ae <a8a7e6a9ff8a4c1f067694ddbd44be67fdf36693; version=f531d13bdfe3f4f084aaa8acae2cb0f02295f5ae <d0a4dc7efa825bce60a8da8f7d43c864a159abde

Published CVSS scores

7.0Red HatCVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:H
9.8Linux CNACVSS:3.1/AV:N/AC:L/PR:N/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 exploitPublished

Weakness, pattern, technique

CWE-1341Multiple Releases of Same Resource or Handle
T1068Exploitation for Privilege Escalation

Public exploit references

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

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Your stack

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