CVE-2026-72320Network attack vector

Firewall policy bypass via stale inverted-lookup result

Published Aug 15, 2026 · Updated Aug 15, 2026

Incorrect comparison in the Linux kernel netfilter nft_lookup component allows remote attackers to bypass configured packet-filtering rules. The nft_lookup_eval() function computes found before replacing a failed direct lookup with an interval-set catchall, then applies inversion to the stale result. Triggering requires an inverted nftables lookup over an interval set with an open-ended catchall; affected packets can be admitted or dropped contrary to policy.

CVSS severity9.1
Critical
EPSS probability0.52%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Incorrect comparison in the Linux kernel netfilter nft_lookup component allows remote attackers to bypass configured packet-filtering rules. The nft_lookup_eval() function computes found before replacing a failed direct lookup with an interval-set catchall, then applies inversion to the stale result. Triggering requires an inverted nftables lookup over an interval set with an open-ended catchall; affected packets can be admitted or dropped contrary to policy.

The record

CVE
CVE-2026-72320
Published
Aug 15, 2026
Updated
Aug 15, 2026
Vendor
The Linux Kernel Organization
Product
Linux
Classifications
CWE-1025, T1562.004
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=5.13
  2. Affected versionversion=aaa31047a6d25da0fa101da1ed544e1247949b40 <0ab8880865f9678eb6174e72c1fc4712e44c745c
  3. Affected versionversion=aaa31047a6d25da0fa101da1ed544e1247949b40 <238c612357b5a25f03eacf356f95034f8551f218
  4. Affected versionversion=aaa31047a6d25da0fa101da1ed544e1247949b40 <e6107a4c74b54cb33e3bce162a63048ae5a6b198
  5. Affected versionversion=aaa31047a6d25da0fa101da1ed544e1247949b40 <ef0c7d4b04a0e6ad175323c24bc84e11470dd79d

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

The Linux Kernel Organization · Linuxversion=5.13; version=aaa31047a6d25da0fa101da1ed544e1247949b40 <0ab8880865f9678eb6174e72c1fc4712e44c745c; version=aaa31047a6d25da0fa101da1ed544e1247949b40 <238c612357b5a25f03eacf356f95034f8551f218; version=aaa31047a6d25da0fa101da1ed544e1247949b40 <e6107a4c74b54cb33e3bce162a63048ae5a6b198; version=aaa31047a6d25da0fa101da1ed544e1247949b40 <ef0c7d4b04a0e6ad175323c24bc84e11470dd79d

Published CVSS scores

9.1Linux Kernel CNACVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N
7.0OracleCVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:H
7.0Red HatCVSS: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)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-1025Comparison Using Wrong Factors
T1562.004Disable or Modify System Firewall

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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