CVE-2026-72256
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.
Affected versions
Linux kernel versions
2.6.30
and later are affected. Fixed in
5.10.261,
5.15.212,
6.1.178,
6.6.145,
6.12.97,
6.18.40,
7.1.5,
7.2-rc1
and their respective stable series.
References
8 totalFrequently asked questions
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What is CVE-2026-72256?
CVE-2026-72256 is a unscored severity Linux kernel vulnerability . It affects Linux kernel versions from 2.6.30 onward and has been patched in 5.10.261, 5.15.212, 6.1.178 and others. CVE-2026-72256 has not been confirmed as actively exploited and is not listed in the CISA KEV catalog.
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Is there a patch available for CVE-2026-72256?
Yes. CVE-2026-72256 has been patched. Fixed versions include 5.10.261, 5.15.212, 6.1.178 and others. If you are running Linux kernel 2.6.30 or later up to the fix versions, apply the relevant patch for your kernel branch.
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Is CVE-2026-72256 actively exploited?
No. CVE-2026-72256 has not been confirmed as actively exploited. It is not listed in the CISA Known Exploited Vulnerabilities (KEV) catalog.