CVE-2026-72418Network attack vector

Service interruption via connlimit connection miscounting

Published Aug 15, 2026 · Updated Aug 15, 2026

A netfilter connlimit flaw in the Linux kernel allows remote attackers to interrupt valid connections when sockets in TIME_WAIT are reused. __nf_conncount_add() treats an early-confirmed entry as already counted, skips insertion, and triggers garbage collection; xt_connlimit then mishandles the resulting zero count and rejects the new connection. The target must use connlimit for soft limiting, and the connection must reuse a TIME_WAIT socket or enter a comparable early-confirmed setup state.

CVSS severity7.5
High
EPSS probability0.71%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

A netfilter connlimit flaw in the Linux kernel allows remote attackers to interrupt valid connections when sockets in TIME_WAIT are reused. __nf_conncount_add() treats an early-confirmed entry as already counted, skips insertion, and triggers garbage collection; xt_connlimit then mishandles the resulting zero count and rejects the new connection. The target must use connlimit for soft limiting, and the connection must reuse a TIME_WAIT socket or enter a comparable early-confirmed setup state.

The record

CVE
CVE-2026-72418
Published
Aug 15, 2026
Updated
Aug 15, 2026
Vendor
The Linux Kernel Organization
Product
Linux
Classifications
CWE-367, T1499.004
Attack vector
network
Privileges
unauthenticated

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=460c112e1d887b58b06b56e8e0230058906ff2c3 <000ac6830b56499d6b65fd91486ce6689eb02be4
  2. Affected versionversion=5.10.248 <5.10.261
  3. Affected versionversion=5.15.198 <5.15.212
  4. Affected versionversion=53bc0ac47f4f7621c991807bc90e01df49561ac8 <cbe2d14a7c5b1fc71821fbfee5c4963917411e92
  5. Affected versionversion=6.1.160 <6.1.178
  6. Affected versionversion=6.12.63 <6.12.97
  7. Affected versionversion=6.17.13 <6.18
  8. Affected versionversion=6.18.2 <6.18.40
  9. Affected versionversion=6.19
  10. Affected versionversion=6.6.120 <6.6.145
  11. Affected versionversion=69894e5b4c5e28cda5f32af33d4a92b7a4b93b0e <be52572c6d55f677ba76869d3c63805c0d4891a3
  12. Affected versionversion=69894e5b4c5e28cda5f32af33d4a92b7a4b93b0e <c8b6f36f766991e3ebebec6596daee4b04dcbc49
  13. Affected versionversion=77ea3d8ac3d3d59b5ac9ad639e4ba107c0f2ff1e <329f2626ee5cb8fafdf6b58b624311529c57cb45
  14. Affected versionversion=8286c02fe9100330475331253fc590f047963f90 <abef7f817217fcb62c11821d6b895063eadb2828
  15. Affected versionversion=b29ddccf36946a90323486221f39e9f88cc01b8e <ebfe8249ba79e4ff0f1e3aad8787b992ef27f026
  16. Affected versionversion=ca8b4d1d6304a84ce2016fa2fe9a114b9607b839 <3793d24de224943e0a6016bbeffb6f5c4cea2e3d
  17. Affected versionversion=f85623af16b83615e5f64a9b19ae1d584805cb07

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

The Linux Kernel Organization · Linuxversion=460c112e1d887b58b06b56e8e0230058906ff2c3 <000ac6830b56499d6b65fd91486ce6689eb02be4; version=5.10.248 <5.10.261; version=5.15.198 <5.15.212; version=53bc0ac47f4f7621c991807bc90e01df49561ac8 <cbe2d14a7c5b1fc71821fbfee5c4963917411e92; version=6.1.160 <6.1.178; version=6.12.63 <6.12.97; version=6.17.13 <6.18; version=6.18.2 <6.18.40; version=6.19; version=6.6.120 <6.6.145; version=69894e5b4c5e28cda5f32af33d4a92b7a4b93b0e <be52572c6d55f677ba76869d3c63805c0d4891a3; version=69894e5b4c5e28cda5f32af33d4a92b7a4b93b0e <c8b6f36f766991e3ebebec6596daee4b04dcbc49; version=77ea3d8ac3d3d59b5ac9ad639e4ba107c0f2ff1e <329f2626ee5cb8fafdf6b58b624311529c57cb45; version=8286c02fe9100330475331253fc590f047963f90 <abef7f817217fcb62c11821d6b895063eadb2828; version=b29ddccf36946a90323486221f39e9f88cc01b8e <ebfe8249ba79e4ff0f1e3aad8787b992ef27f026; version=ca8b4d1d6304a84ce2016fa2fe9a114b9607b839 <3793d24de224943e0a6016bbeffb6f5c4cea2e3d; version=f85623af16b83615e5f64a9b19ae1d584805cb07

Published CVSS scores

7.5Linux CNA via cve.orgCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
5.5Red HatCVSS:3.1/AV:L/AC:L/PR:L/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-367Time-of-check Time-of-use (TOCTOU) Race Condition
T1499.004Endpoint Denial of Service: Application 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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