CVE-2026-72256

Summary

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 Software

VendorProductVersion RangeStatus
LinuxLinux0269ea4937343536ec7e85649932bc8c9686ea78 < 4558bd7b47c7be82dffd837f27be8ea3ecee557daffected
LinuxLinux0269ea4937343536ec7e85649932bc8c9686ea78 < d5f9d050b0b267227c1f02f11021872c7768a9ccaffected
LinuxLinux0269ea4937343536ec7e85649932bc8c9686ea78 < 4cb8b5f586e41c187942291cc0938006077fa79eaffected
LinuxLinux0269ea4937343536ec7e85649932bc8c9686ea78 < fac2fdac3baad9ffd12b3b0bba4374d4b3585d54affected
LinuxLinux0269ea4937343536ec7e85649932bc8c9686ea78 < 13ea4f86cf738c74be2146886ac261988a631e62affected
LinuxLinux0269ea4937343536ec7e85649932bc8c9686ea78 < 07f9ddbf5e799c24a3a52ec9bd7b729a6f6d69d5affected
LinuxLinux0269ea4937343536ec7e85649932bc8c9686ea78 < 5b2d4f0010018a7aa3495aa1dbf1b7a34011e7aaaffected
LinuxLinux0269ea4937343536ec7e85649932bc8c9686ea78 < 5feba91006ec92da57acc1cc2e34df623b98541eaffected
LinuxLinux2.6.30affected
LinuxLinux0 < 2.6.30unaffected
LinuxLinux5.10.261 <= 5.10.*unaffected
LinuxLinux5.15.212 <= 5.15.*unaffected
LinuxLinux6.1.178 <= 6.1.*unaffected
LinuxLinux6.6.145 <= 6.6.*unaffected
LinuxLinux6.12.97 <= 6.12.*unaffected
LinuxLinux6.18.40 <= 6.18.*unaffected
LinuxLinux7.1.5 <= 7.1.*unaffected
LinuxLinux7.2 <= *unaffected

Weaknesses

References