CVE-2026-72221

Local denial of service via TLS callback race

Published Aug 15, 2026 · Updated Aug 15, 2026

Race condition in SUNRPC transport TLS handshakes in affected Linux kernels allows local users to corrupt kernel state or interrupt service. The svc_tcp_handshake function inspects xpt_flags after cancellation loses to handshake_complete but before svc_tcp_handshake_done commits its callback effects, permitting a second handshake to reinitialize a completion object concurrently. Triggering requires local low-privileged access and a high-complexity timeout or signal race; outcomes include premature connection teardown, swait-queue corruption, and system instability.

CVSS severity7.0
High
EPSS probability0.63%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Race condition in SUNRPC transport TLS handshakes in affected Linux kernels allows local users to corrupt kernel state or interrupt service. The svc_tcp_handshake function inspects xpt_flags after cancellation loses to handshake_complete but before svc_tcp_handshake_done commits its callback effects, permitting a second handshake to reinitialize a completion object concurrently. Triggering requires local low-privileged access and a high-complexity timeout or signal race; outcomes include premature connection teardown, swait-queue corruption, and system instability.

The record

CVE
CVE-2026-72221
Published
Aug 15, 2026
Updated
Aug 15, 2026
Vendor
The Linux Kernel Organization
Product
Linux
Classifications
CWE-366, T1499
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=6.4
  2. Affected versionversion=b3cbf98e2fdf3cb147a95161560cd25987284330 <0d8ceb39884148dc7a2fdf71e1cac5961ed1d2b9
  3. Affected versionversion=b3cbf98e2fdf3cb147a95161560cd25987284330 <65b23bec1fca6e9ebdc3e6041ebf8c6ab074141b
  4. Affected versionversion=b3cbf98e2fdf3cb147a95161560cd25987284330 <a4f878e8ecd729ccf2e50993444e217583adeace
  5. Affected versionversion=b3cbf98e2fdf3cb147a95161560cd25987284330 <d00e32f84ca1a77cb67a3fbf59f58dada95f5a21
  6. Affected versionversion=b3cbf98e2fdf3cb147a95161560cd25987284330 <e0f4691d42a54d359d8b64509fd9ab938d4f2a33

What conditions does exploitation require?

Attack vectorlocal
Required privilegesauthenticated

What is affected?

The Linux Kernel Organization · Linuxversion=6.4; version=b3cbf98e2fdf3cb147a95161560cd25987284330 <0d8ceb39884148dc7a2fdf71e1cac5961ed1d2b9; version=b3cbf98e2fdf3cb147a95161560cd25987284330 <65b23bec1fca6e9ebdc3e6041ebf8c6ab074141b; version=b3cbf98e2fdf3cb147a95161560cd25987284330 <a4f878e8ecd729ccf2e50993444e217583adeace; version=b3cbf98e2fdf3cb147a95161560cd25987284330 <d00e32f84ca1a77cb67a3fbf59f58dada95f5a21; version=b3cbf98e2fdf3cb147a95161560cd25987284330 <e0f4691d42a54d359d8b64509fd9ab938d4f2a33

Published CVSS scores

5.3Amazon LinuxCVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:N/I:L/A:H
7.0Oracle LinuxCVSS:3.1/AV:L/AC:H/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

CWE-366Race Condition within a Thread
T1499Endpoint Denial of Service

Public exploit references

No public exploit references are available in this record.

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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