CVE-2026-80664: netfilter: xt_nat: reject unsupported target families
In the Linux kernel, the following vulnerability has been resolved:
netfilter: xtnat: reject unsupported target families
xtnat SNAT and DNAT target handlers assume IP-family conntrack state is present and can dereference a NULL pointer when instantiated from an unsupported family through nftcompat. A bridge-family compat rule can therefore trigger a NULL-dereference in nfnatsetupinfo().
Reject non-IP families in xtnatcheckentry() so unsupported targets cannot be installed. Keep NFPROTOINET allowed for valid inet NAT compat users and leave the runtime fast path unchanged.
[ The crash was fixed via 9dbba7e694ec ("netfilter: nftcompat: ebtables emulation must reject non-bridge targets"), so this patch is no longer critical. Nevertheless, NAT is only relevant for ipv4/ipv6, so this extra family check is a good idea in any case. ]
Affected Software
Remediation
Recommended actions to resolve this vulnerability, in priority order.
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ubuntu/linux-oracleto a version that resolves this vulnerability.Fixed in 6.8.0-1064.67 - Upgrade
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ubuntu/linux-oracle-7.0to a version that resolves this vulnerability.Fixed in 7.0.0-1013.13~24.04.1 - Upgrade
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ubuntu/linux-bluefieldto a version that resolves this vulnerability.Fixed in 6.8.0-1033.38 - Upgrade
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ubuntu/linux-realtimeto a version that resolves this vulnerability.Fixed in 6.8.1-1062.63 - Upgrade
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ubuntu/linux-aws-fipsto a version that resolves this vulnerability.Fixed in 6.8.0-1067.70+fips1 - Upgrade
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ubuntu/linux-azure-fipsto a version that resolves this vulnerability.Fixed in 6.8.0-1071.79+fips1 - Upgrade
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ubuntu/linux-fipsto a version that resolves this vulnerability.Fixed in 6.8.0-147.147+fips1 - Upgrade
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ubuntu/linux-gcp-fipsto a version that resolves this vulnerability.Fixed in 6.8.0-1071.79+fips1 - Upgrade
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ubuntu/linuxto a version that resolves this vulnerability.Fixed in 7.0.0-38.38 - Upgrade
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ubuntu/linux-awsto a version that resolves this vulnerability.Fixed in 7.0.0-1014.14 - Upgrade
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ubuntu/linux-azureto a version that resolves this vulnerability.Fixed in 7.0.0-1017.17 - Upgrade
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ubuntu/linux-azure-fdeto a version that resolves this vulnerability.Fixed in 7.0.0-1016.16 - Upgrade
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ubuntu/linux-gcpto a version that resolves this vulnerability.Fixed in 7.0.0-1014.14 - Upgrade
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Patch 9dbba7e694ec
Event History
Frequently Asked Questions
Which systems are exposed to the NULL dereference?
Exposure requires xt_nat SNAT or DNAT targets to be instantiated from an unsupported protocol family through nft_compat. The described case is a bridge-family compatibility rule; NAT targets are relevant only to IPv4 and IPv6 families.
What access or condition is needed to trigger the crash?
A bridge-family nft_compat rule must be able to install an unsupported xt_nat target. When that target is used, the handler can assume IP-family conntrack state exists and dereference a NULL pointer in nf_nat_setup_info().
Is this still considered critical if the newer family validation is not present?
The description states that the crash was already fixed by commit 9dbba7e694ec, which made nft_compat ebtables emulation reject non-bridge targets. The additional xt_nat family check is described as defense in depth and no longer critical after that earlier fix.
How can I identify a potentially affected configuration?
Review nft_compat and ebtables-emulation rules for bridge-family rules that use xt_nat SNAT or DNAT compatibility targets. Such non-IP-family NAT target use is the configuration the new check rejects.