CVE-2026-72256

netfilter: xt_cluster: reject template conntracks in hash match

N/A

Published: August 15, 2026 at 05:54 AM UTC

Updated: August 17, 2026 at 06:18 AM UTC

1 product affected across 1 vendorLinux Kernel

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Severity

N/A

Exploit prediction

EPSS 0.2%

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.

Affected

Our own answer: ranges merged, affected separated from platform-only, with confidence and review flags.

Linux Kernel · Linux

95%

2.6.30 ≤ v < 5.10.2612.6.30 ≤ v < 5.15.2122.6.30 ≤ v < 6.1.1782.6.30 ≤ v < 6.12.972.6.30 ≤ v < 6.18.402.6.30 ≤ v < 6.6.1452.6.30 ≤ v < 7.1.52.6.30 ≤ v < 7.22.6.30269ea4937343536ec7e85649932bc8c9686ea78

Vendor states this is fixed in 07f9ddbf5e799c24a3a52ec9bd7b729a6f6d69d5 (fixed)

Vendor states this is fixed in 13ea4f86cf738c74be2146886ac261988a631e62 (fixed)

Vendor states this is fixed in 4558bd7b47c7be82dffd837f27be8ea3ecee557d (fixed)

Vendor states this is fixed in 4cb8b5f586e41c187942291cc0938006077fa79e (fixed)

Vendor states this is fixed in 5b2d4f0010018a7aa3495aa1dbf1b7a34011e7aa (fixed)

Vendor states this is fixed in 5feba91006ec92da57acc1cc2e34df623b98541e (fixed)

Vendor states this is fixed in d5f9d050b0b267227c1f02f11021872c7768a9cc (fixed)

Vendor states this is fixed in fac2fdac3baad9ffd12b3b0bba4374d4b3585d54 (fixed)

Vendor states this is fixed in 2.6.30 (unaffected)

Vendor states this is fixed in 5.10.261 (unaffected)

Vendor states this is fixed in 5.15.212 (unaffected)

Vendor states this is fixed in 6.1.178 (unaffected)