CVE-2026-74696Network attack vector

Denial of service via Fast Open queue undercount

Published Aug 22, 2026 · Updated Aug 25, 2026

Denial of service in affected Linux kernel releases allows remote attackers to exhaust resources through excessive TCP Fast Open requests. The TCP Fast Open path charges fastopenq.qlen on the original listener, but migration repoints the child request so completion decrements the surviving listener and drives its counter negative. Server-side TCP Fast Open and SO_REUSEPORT listener migration during worker closure are required; the bypassed queue limit permits socket and memory exhaustion that can destabilize the host.

CVSS severity7.5
High
EPSS probability0.49%
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 affected Linux kernel releases allows remote attackers to exhaust resources through excessive TCP Fast Open requests. The TCP Fast Open path charges fastopenq.qlen on the original listener, but migration repoints the child request so completion decrements the surviving listener and drives its counter negative. Server-side TCP Fast Open and SO_REUSEPORT listener migration during worker closure are required; the bypassed queue limit permits socket and memory exhaustion that can destabilize the host.

The record

CVE
CVE-2026-74696
Published
Aug 22, 2026
Updated
Aug 25, 2026
Vendor
The Linux Kernel Organization
Product
Linux
Classifications
CWE-191, T1499.004
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Aug 22, 2026CVE publishedPublication date reported by the CVE source.
  2. Aug 25, 2026Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

Compare your product and version with the public record. A matching version still requires validation against your environment.

Is a vulnerable build present?

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

  1. Affected versionversion=5.14
  2. Affected versionversion=54b92e84193749c9968aff2dd46e3b0f42643e18 <585fc5247d14939a561056aa2addd9b7c2b1f670
  3. Affected versionversion=54b92e84193749c9968aff2dd46e3b0f42643e18 <6e10ee56524a26b250229ad348637825646ddb88
  4. Affected versionversion=54b92e84193749c9968aff2dd46e3b0f42643e18 <a0ab2ba83e35159d81cec830a92e885ecf8139be
  5. Affected versionversion=54b92e84193749c9968aff2dd46e3b0f42643e18 <a66e869cf0c90c1e47ae75f72b6482acbfc808ff
  6. Affected versionversion=54b92e84193749c9968aff2dd46e3b0f42643e18 <b6247e0f96bd825ffb2005257f6177b5e642dee6
  7. Affected versionversion=54b92e84193749c9968aff2dd46e3b0f42643e18 <d974618b2097453778389d385e3741629c40e0a3
  8. Affected versionversion=54b92e84193749c9968aff2dd46e3b0f42643e18 <e98f0d80b9cccb5f828425d2004f9686e7d1ae24

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

The Linux Kernel Organization · Linuxversion=5.14; version=54b92e84193749c9968aff2dd46e3b0f42643e18 <585fc5247d14939a561056aa2addd9b7c2b1f670; version=54b92e84193749c9968aff2dd46e3b0f42643e18 <6e10ee56524a26b250229ad348637825646ddb88; version=54b92e84193749c9968aff2dd46e3b0f42643e18 <a0ab2ba83e35159d81cec830a92e885ecf8139be; version=54b92e84193749c9968aff2dd46e3b0f42643e18 <a66e869cf0c90c1e47ae75f72b6482acbfc808ff; version=54b92e84193749c9968aff2dd46e3b0f42643e18 <b6247e0f96bd825ffb2005257f6177b5e642dee6; version=54b92e84193749c9968aff2dd46e3b0f42643e18 <d974618b2097453778389d385e3741629c40e0a3; version=54b92e84193749c9968aff2dd46e3b0f42643e18 <e98f0d80b9cccb5f828425d2004f9686e7d1ae24

Published CVSS scores

7.5Linux Kernel CVE TeamCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/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 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-191Integer Underflow (Wrap or Wraparound)
T1499.004Application or System Exploitation

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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