CVE Catalog

CVE-2026-72256

Low risk· EPSS 12%
Published: Updated: Translated: NVD NIST

Exploitation Probability (EPSS)

Low risk
0.21%

12th percentile - higher than 12% of all known CVEs

Summary

In the Linux kernel, a bug was found in netfilter xt_cluster where template conntracks are treated as fully initialized 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(). 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. The fix rejects template conntracks before hashing them.

Risk Assessment

The bug can lead to kernel warnings, crashes, or incorrect packet filtering, potentially affecting network security.

Recommendation

It is recommended to update the Linux kernel to a version containing the fix that rejects template conntracks in xt_cluster_mt().

Other vulnerabilities in Linux kernel

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Original NVD description (English source)

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.

Vulnerability data from NVD (NIST) · CISA KEV · EPSS