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CVE-2026-72256
netfilter: xt_cluster: reject template conntracks in hash match
Overview
Description

In the Linux kernel, the following vulnerability has been resolved: netfilter: xt_cluster: reject template conntracks in hash match xt_cluster_mt() treats any non-NULL nf_ct_get() result as a fully initialized conntrack and passes it to xt_cluster_hash(). This causes a state confusion bug when the raw table CT target attaches a template conntrack to skb->_nfct before normal conntrack processing. Templates carry IPS_TEMPLATE status but do not have a valid tuple for hashing yet, so xt_cluster_hash() can hit its WARN_ON() path on the zeroed l3num field. Reject template conntracks before hashing them. This matches existing netfilter handling for template objects and avoids hashing incomplete conntrack state.

Details
INFO

Published Date :

Aug. 15, 2026, 6:21 a.m.

Last Modified :

Aug. 17, 2026, 6:18 a.m.

Remotely Exploit :

No

Source :

416baaa9-dc9f-4396-8d5f-8c081fb06d67
Impact
Affected Products

The following products are affected by CVE-2026-72256 vulnerability. Even if cvefeed.io is aware of the exact versions of the products that are affected, the information is not represented in the table below.

ID Vendor Product Action
1 Linux linux_kernel
: Total Affected Vendor : 1 | Products : 1
Solution
Reject template conntracks before hashing to avoid state confusion.
  • Update the Linux kernel to the latest version.
  • Apply the netfilter: xt_cluster patch.
  • Ensure conntrack processing handles template objects correctly.
  • Verify hashing logic for incomplete conntrack state.
References
References to Advisories, Solutions, and Tools

Here, you will find a curated list of external links that provide in-depth information, practical solutions, and valuable tools related to CVE-2026-72256.

URL Resource
https://git.kernel.org/stable/c/07f9ddbf5e799c24a3a52ec9bd7b729a6f6d69d5
https://git.kernel.org/stable/c/13ea4f86cf738c74be2146886ac261988a631e62
https://git.kernel.org/stable/c/4558bd7b47c7be82dffd837f27be8ea3ecee557d
https://git.kernel.org/stable/c/4cb8b5f586e41c187942291cc0938006077fa79e
https://git.kernel.org/stable/c/5b2d4f0010018a7aa3495aa1dbf1b7a34011e7aa
https://git.kernel.org/stable/c/5feba91006ec92da57acc1cc2e34df623b98541e
https://git.kernel.org/stable/c/d5f9d050b0b267227c1f02f11021872c7768a9cc
https://git.kernel.org/stable/c/fac2fdac3baad9ffd12b3b0bba4374d4b3585d54
CWE - Common Weakness Enumeration

While CVE identifies specific instances of vulnerabilities, CWE categorizes the common flaws or weaknesses that can lead to vulnerabilities. CVE-2026-72256 is associated with the following CWEs:

Common Attack Pattern Enumeration and Classification (CAPEC)

Common Attack Pattern Enumeration and Classification (CAPEC) stores attack patterns, which are descriptions of the common attributes and approaches employed by adversaries to exploit the CVE-2026-72256 weaknesses.

We scan GitHub repositories to detect new proof-of-concept exploits. Following list is a collection of public exploits and proof-of-concepts, which have been published on GitHub (sorted by the most recently updated).

Results are limited to the first 15 repositories due to potential performance issues.

The following list is the news that have been mention CVE-2026-72256 vulnerability anywhere in the article.

Results are limited to the first 20 news articles due to potential performance issues.

The following table lists the changes that have been made to the CVE-2026-72256 vulnerability over time.

Vulnerability history details can be useful for understanding the evolution of a vulnerability, and for identifying the most recent changes that may impact the vulnerability's severity, exploitability, or other characteristics.

  • CVE Modified by 416baaa9-dc9f-4396-8d5f-8c081fb06d67

    Aug. 17, 2026

    Action Type Old Value New Value
    Changed Affected [{'repo': 'https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git', 'vendor': 'Linux', 'product': 'Linux', 'versions': [{'status': 'affected', 'version': '0269ea4937343536ec7e85649932bc8c9686ea78', 'lessThan': '4558bd7b47c7be82dffd837f27be8ea3ecee557d', 'versionType': 'git'}, {'status': 'affected', 'version': '0269ea4937343536ec7e85649932bc8c9686ea78', 'lessThan': 'd5f9d050b0b267227c1f02f11021872c7768a9cc', 'versionType': 'git'}, {'status': 'affected', 'version': '0269ea4937343536ec7e85649932bc8c9686ea78', 'lessThan': '4cb8b5f586e41c187942291cc0938006077fa79e', 'versionType': 'git'}, {'status': 'affected', 'version': '0269ea4937343536ec7e85649932bc8c9686ea78', 'lessThan': 'fac2fdac3baad9ffd12b3b0bba4374d4b3585d54', 'versionType': 'git'}, {'status': 'affected', 'version': '0269ea4937343536ec7e85649932bc8c9686ea78', 'lessThan': '13ea4f86cf738c74be2146886ac261988a631e62', 'versionType': 'git'}, {'status': 'affected', 'version': '0269ea4937343536ec7e85649932bc8c9686ea78', 'lessThan': '07f9ddbf5e799c24a3a52ec9bd7b729a6f6d69d5', 'versionType': 'git'}, {'status': 'affected', 'version': '0269ea4937343536ec7e85649932bc8c9686ea78', 'lessThan': '5b2d4f0010018a7aa3495aa1dbf1b7a34011e7aa', 'versionType': 'git'}, {'status': 'affected', 'version': '0269ea4937343536ec7e85649932bc8c9686ea78', 'lessThan': '5feba91006ec92da57acc1cc2e34df623b98541e', 'versionType': 'git'}], 'programFiles': ['net/netfilter/xt_cluster.c'], 'defaultStatus': 'unaffected'}, {'repo': 'https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git', 'vendor': 'Linux', 'product': 'Linux', 'versions': [{'status': 'affected', 'version': '2.6.30'}, {'status': 'unaffected', 'version': '0', 'lessThan': '2.6.30', 'versionType': 'semver'}, {'status': 'unaffected', 'version': '5.10.261', 'versionType': 'semver', 'lessThanOrEqual': '5.10.*'}, {'status': 'unaffected', 'version': '5.15.212', 'versionType': 'semver', 'lessThanOrEqual': '5.15.*'}, {'status': 'unaffected', 'version': '6.1.178', 'versionType': 'semver', 'lessThanOrEqual': '6.1.*'}, {'status': 'unaffected', 'version': '6.6.145', 'versionType': 'semver', 'lessThanOrEqual': '6.6.*'}, {'status': 'unaffected', 'version': '6.12.97', 'versionType': 'semver', 'lessThanOrEqual': '6.12.*'}, {'status': 'unaffected', 'version': '6.18.40', 'versionType': 'semver', 'lessThanOrEqual': '6.18.*'}, {'status': 'unaffected', 'version': '7.1.5', 'versionType': 'semver', 'lessThanOrEqual': '7.1.*'}, {'status': 'unaffected', 'version': '7.2-rc1', 'versionType': 'original_commit_for_fix', 'lessThanOrEqual': '*'}], 'programFiles': ['net/netfilter/xt_cluster.c'], 'defaultStatus': 'affected'}] [{'repo': 'https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git', 'vendor': 'Linux', 'product': 'Linux', 'versions': [{'status': 'affected', 'version': '0269ea4937343536ec7e85649932bc8c9686ea78', 'lessThan': '4558bd7b47c7be82dffd837f27be8ea3ecee557d', 'versionType': 'git'}, {'status': 'affected', 'version': '0269ea4937343536ec7e85649932bc8c9686ea78', 'lessThan': 'd5f9d050b0b267227c1f02f11021872c7768a9cc', 'versionType': 'git'}, {'status': 'affected', 'version': '0269ea4937343536ec7e85649932bc8c9686ea78', 'lessThan': '4cb8b5f586e41c187942291cc0938006077fa79e', 'versionType': 'git'}, {'status': 'affected', 'version': '0269ea4937343536ec7e85649932bc8c9686ea78', 'lessThan': 'fac2fdac3baad9ffd12b3b0bba4374d4b3585d54', 'versionType': 'git'}, {'status': 'affected', 'version': '0269ea4937343536ec7e85649932bc8c9686ea78', 'lessThan': '13ea4f86cf738c74be2146886ac261988a631e62', 'versionType': 'git'}, {'status': 'affected', 'version': '0269ea4937343536ec7e85649932bc8c9686ea78', 'lessThan': '07f9ddbf5e799c24a3a52ec9bd7b729a6f6d69d5', 'versionType': 'git'}, {'status': 'affected', 'version': '0269ea4937343536ec7e85649932bc8c9686ea78', 'lessThan': '5b2d4f0010018a7aa3495aa1dbf1b7a34011e7aa', 'versionType': 'git'}, {'status': 'affected', 'version': '0269ea4937343536ec7e85649932bc8c9686ea78', 'lessThan': '5feba91006ec92da57acc1cc2e34df623b98541e', 'versionType': 'git'}], 'programFiles': ['net/netfilter/xt_cluster.c'], 'defaultStatus': 'unaffected'}, {'repo': 'https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git', 'vendor': 'Linux', 'product': 'Linux', 'versions': [{'status': 'affected', 'version': '2.6.30'}, {'status': 'unaffected', 'version': '0', 'lessThan': '2.6.30', 'versionType': 'semver'}, {'status': 'unaffected', 'version': '5.10.261', 'versionType': 'semver', 'lessThanOrEqual': '5.10.*'}, {'status': 'unaffected', 'version': '5.15.212', 'versionType': 'semver', 'lessThanOrEqual': '5.15.*'}, {'status': 'unaffected', 'version': '6.1.178', 'versionType': 'semver', 'lessThanOrEqual': '6.1.*'}, {'status': 'unaffected', 'version': '6.6.145', 'versionType': 'semver', 'lessThanOrEqual': '6.6.*'}, {'status': 'unaffected', 'version': '6.12.97', 'versionType': 'semver', 'lessThanOrEqual': '6.12.*'}, {'status': 'unaffected', 'version': '6.18.40', 'versionType': 'semver', 'lessThanOrEqual': '6.18.*'}, {'status': 'unaffected', 'version': '7.1.5', 'versionType': 'semver', 'lessThanOrEqual': '7.1.*'}, {'status': 'unaffected', 'version': '7.2', 'versionType': 'original_commit_for_fix', 'lessThanOrEqual': '*'}], 'programFiles': ['net/netfilter/xt_cluster.c'], 'defaultStatus': 'affected'}]
  • New CVE Received by 416baaa9-dc9f-4396-8d5f-8c081fb06d67

    Aug. 15, 2026

    Action Type Old Value New Value
    Added Affected [{'repo': 'https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git', 'vendor': 'Linux', 'product': 'Linux', 'versions': [{'status': 'affected', 'version': '0269ea4937343536ec7e85649932bc8c9686ea78', 'lessThan': '4558bd7b47c7be82dffd837f27be8ea3ecee557d', 'versionType': 'git'}, {'status': 'affected', 'version': '0269ea4937343536ec7e85649932bc8c9686ea78', 'lessThan': 'd5f9d050b0b267227c1f02f11021872c7768a9cc', 'versionType': 'git'}, {'status': 'affected', 'version': '0269ea4937343536ec7e85649932bc8c9686ea78', 'lessThan': '4cb8b5f586e41c187942291cc0938006077fa79e', 'versionType': 'git'}, {'status': 'affected', 'version': '0269ea4937343536ec7e85649932bc8c9686ea78', 'lessThan': 'fac2fdac3baad9ffd12b3b0bba4374d4b3585d54', 'versionType': 'git'}, {'status': 'affected', 'version': '0269ea4937343536ec7e85649932bc8c9686ea78', 'lessThan': '13ea4f86cf738c74be2146886ac261988a631e62', 'versionType': 'git'}, {'status': 'affected', 'version': '0269ea4937343536ec7e85649932bc8c9686ea78', 'lessThan': '07f9ddbf5e799c24a3a52ec9bd7b729a6f6d69d5', 'versionType': 'git'}, {'status': 'affected', 'version': '0269ea4937343536ec7e85649932bc8c9686ea78', 'lessThan': '5b2d4f0010018a7aa3495aa1dbf1b7a34011e7aa', 'versionType': 'git'}, {'status': 'affected', 'version': '0269ea4937343536ec7e85649932bc8c9686ea78', 'lessThan': '5feba91006ec92da57acc1cc2e34df623b98541e', 'versionType': 'git'}], 'programFiles': ['net/netfilter/xt_cluster.c'], 'defaultStatus': 'unaffected'}, {'repo': 'https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git', 'vendor': 'Linux', 'product': 'Linux', 'versions': [{'status': 'affected', 'version': '2.6.30'}, {'status': 'unaffected', 'version': '0', 'lessThan': '2.6.30', 'versionType': 'semver'}, {'status': 'unaffected', 'version': '5.10.261', 'versionType': 'semver', 'lessThanOrEqual': '5.10.*'}, {'status': 'unaffected', 'version': '5.15.212', 'versionType': 'semver', 'lessThanOrEqual': '5.15.*'}, {'status': 'unaffected', 'version': '6.1.178', 'versionType': 'semver', 'lessThanOrEqual': '6.1.*'}, {'status': 'unaffected', 'version': '6.6.145', 'versionType': 'semver', 'lessThanOrEqual': '6.6.*'}, {'status': 'unaffected', 'version': '6.12.97', 'versionType': 'semver', 'lessThanOrEqual': '6.12.*'}, {'status': 'unaffected', 'version': '6.18.40', 'versionType': 'semver', 'lessThanOrEqual': '6.18.*'}, {'status': 'unaffected', 'version': '7.1.5', 'versionType': 'semver', 'lessThanOrEqual': '7.1.*'}, {'status': 'unaffected', 'version': '7.2-rc1', 'versionType': 'original_commit_for_fix', 'lessThanOrEqual': '*'}], 'programFiles': ['net/netfilter/xt_cluster.c'], 'defaultStatus': 'affected'}]
    Added Description In the Linux kernel, the following vulnerability has been resolved: netfilter: xt_cluster: reject template conntracks in hash match xt_cluster_mt() treats any non-NULL nf_ct_get() result as a fully initialized conntrack and passes it to xt_cluster_hash(). This causes a state confusion bug when the raw table CT target attaches a template conntrack to skb->_nfct before normal conntrack processing. Templates carry IPS_TEMPLATE status but do not have a valid tuple for hashing yet, so xt_cluster_hash() can hit its WARN_ON() path on the zeroed l3num field. Reject template conntracks before hashing them. This matches existing netfilter handling for template objects and avoids hashing incomplete conntrack state.
    Added Reference https://git.kernel.org/stable/c/07f9ddbf5e799c24a3a52ec9bd7b729a6f6d69d5
    Added Reference https://git.kernel.org/stable/c/13ea4f86cf738c74be2146886ac261988a631e62
    Added Reference https://git.kernel.org/stable/c/4558bd7b47c7be82dffd837f27be8ea3ecee557d
    Added Reference https://git.kernel.org/stable/c/4cb8b5f586e41c187942291cc0938006077fa79e
    Added Reference https://git.kernel.org/stable/c/5b2d4f0010018a7aa3495aa1dbf1b7a34011e7aa
    Added Reference https://git.kernel.org/stable/c/5feba91006ec92da57acc1cc2e34df623b98541e
    Added Reference https://git.kernel.org/stable/c/d5f9d050b0b267227c1f02f11021872c7768a9cc
    Added Reference https://git.kernel.org/stable/c/fac2fdac3baad9ffd12b3b0bba4374d4b3585d54
EPSS is a daily estimate of the probability of exploitation activity being observed over the next 30 days. Following chart shows the EPSS score history of the vulnerability.
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