CVE-2026-45957

System hang via recursive RCU softirq tracing

Published May 27, 2026 · Updated May 27, 2026

Denial of service in Linux Kernel allows local users to hang the system by triggering an RCU softirq deadloop with ftrace enabled. Removal of recursion protection from __rcu_read_unlock lets rcu_read_unlock_special reenter raise_softirq_irqoff before the defer flag is set, causing stack tracing to recurse indefinitely. Reachability requires ftrace and a softirq path through RCU unlock; the resulting recursion consumes kernel execution and hangs the host.

CVSS severity7.1
High
EPSS probability0.13%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Denial of service in Linux Kernel allows local users to hang the system by triggering an RCU softirq deadloop with ftrace enabled. Removal of recursion protection from __rcu_read_unlock lets rcu_read_unlock_special reenter raise_softirq_irqoff before the defer flag is set, causing stack tracing to recurse indefinitely. Reachability requires ftrace and a softirq path through RCU unlock; the resulting recursion consumes kernel execution and hangs the host.

The record

CVE
CVE-2026-45957
Published
May 27, 2026
Updated
May 27, 2026
Vendor
The Linux Kernel Organization
Product
Linux Kernel
Classifications
CWE-125, T1499.004
Attack vector
local
Privileges
authenticated

Timeline

How it unfolded

  1. May 27, 2026CVE publishedPublication date reported by the CVE source.
  2. May 27, 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=5.8
  2. Affected versionversion=5f5fa7ea89dc82d34ed458f4d7a8634e8e9eefce <1f16679a5aa60238466ce339c35f5e82ece60337
  3. Affected versionversion=5f5fa7ea89dc82d34ed458f4d7a8634e8e9eefce <4a4a6e12c9c829be3f74b7206fa8640fc4e1c566
  4. Affected versionversion=5f5fa7ea89dc82d34ed458f4d7a8634e8e9eefce <979c708e6c9d7fc461daef2dad8b45f22e23464c
  5. Affected versionversion=5f5fa7ea89dc82d34ed458f4d7a8634e8e9eefce <c2932e16d8c354404b17123e64daa8e33191e145
  6. Affected versionversion=5f5fa7ea89dc82d34ed458f4d7a8634e8e9eefce <d41e37f26b3157b3f1d10223863519a943aa239b

What conditions does exploitation require?

Attack vectorlocal
Required privilegesauthenticated

What is affected?

The Linux Kernel Organization · Linux Kernelversion=5.8; version=5f5fa7ea89dc82d34ed458f4d7a8634e8e9eefce <1f16679a5aa60238466ce339c35f5e82ece60337; version=5f5fa7ea89dc82d34ed458f4d7a8634e8e9eefce <4a4a6e12c9c829be3f74b7206fa8640fc4e1c566; version=5f5fa7ea89dc82d34ed458f4d7a8634e8e9eefce <979c708e6c9d7fc461daef2dad8b45f22e23464c; version=5f5fa7ea89dc82d34ed458f4d7a8634e8e9eefce <c2932e16d8c354404b17123e64daa8e33191e145; version=5f5fa7ea89dc82d34ed458f4d7a8634e8e9eefce <d41e37f26b3157b3f1d10223863519a943aa239b

Published CVSS scores

7.1NIST NVDCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:N/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 9, 2026Sep 15, 2026
Latest reporting daySep 15, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectorlocal
Privilegesauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-125Out-of-bounds Read
T1499.004Application or System Exploitation

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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