CVE-2026-98490: net: openvswitch: conntrack: fix helper UAF due to extensions realloc
In the Linux kernel, the following vulnerability has been resolved:
net: openvswitch: conntrack: fix helper UAF due to extensions realloc
While calling the helpers, a raw pointer to the extensions area is wired into expectations list:
-> nfcthelper() -> helper->help() -> nfctexpectrelatedreport() -> nfctexpectinsert() -> hlistaddheadrcu(&exp->lnode, &masterhelp->expectations)
In case the connection is not confirmed yet, more extensions can be added afterwards with extadd() calls reallocating the extension space and leaving the now invalid pointer in the expectations list that is later accessed while removing the expectation.
Make sure that helpers are called at the end after all the other extensions are already added.
Note that the helper rejection now leaves the mark and labels set, but that's not different from how the NAT was handled before or how the mark and the labels were handled on confirmation failure. And there are no atomicity guarantees provided by the API anyway.
Affected Software
Remediation
Recommended actions to resolve this vulnerability, in priority order.
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debian/linuxto a version that resolves this vulnerability.Fixed in 6.12.113-1 - Upgrade
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debian/linuxto a version that resolves this vulnerability.Fixed in 7.2.9-1 - Upgrade
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debian/linux-6.12to a version that resolves this vulnerability.Fixed in 6.12.113-1~deb12u1 - Upgrade
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linux/Kernelto a version that resolves this vulnerability.Fixed in 5.10.273 - Upgrade
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linux/Kernelto a version that resolves this vulnerability.Fixed in 5.15.224 - Upgrade
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linux/Kernelto a version that resolves this vulnerability.Fixed in 6.1.191 - Upgrade
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linux/Kernelto a version that resolves this vulnerability.Fixed in 6.6.160 - Upgrade
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linux/Kernelto a version that resolves this vulnerability.Fixed in 6.12.112 - Upgrade
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linux/Kernelto a version that resolves this vulnerability.Fixed in 6.18.55 - Upgrade
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linux/Kernelto a version that resolves this vulnerability.Fixed in 7.2.9 - Upgrade
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debian/linuxto a version that resolves this vulnerability.Fixed in 6.12.115-2Fixed in 7.2.12-1Fixed in 7.2.15-1 - Upgrade
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ubuntu/linux-hwe-7.0to a version that resolves this vulnerability.Fixed in 7.0.0-42.42~24.04.1 - Upgrade
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ubuntu/linux-riscv-7.0to a version that resolves this vulnerability.Fixed in 7.0.0-42.42.1~24.04.1 - Upgrade
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ubuntu/linuxto a version that resolves this vulnerability.Fixed in 7.0.0-42.42 - Upgrade
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ubuntu/linux-awsto a version that resolves this vulnerability.Fixed in 7.0.0-1016.17 - Upgrade
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ubuntu/linux-gcpto a version that resolves this vulnerability.Fixed in 7.0.0-1016.18 - Upgrade
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ubuntu/linux-ibmto a version that resolves this vulnerability.Fixed in 7.0.0-1017.17 - Upgrade
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ubuntu/linux-oem-7.0to a version that resolves this vulnerability.Fixed in 7.0.0-1017.17 - Upgrade
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ubuntu/linux-oracleto a version that resolves this vulnerability.Fixed in 7.0.0-1015.16 - Upgrade
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ubuntu/linux-riscvto a version that resolves this vulnerability.Fixed in 7.0.0-42.42.1 - Upgrade
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azurelinux/kernelto a version that resolves this vulnerability.Fixed in 6.6.161.1-1 - Compensating control
Call conntrack helpers at the end, after all other extensions have been added, to prevent extension-space reallocation from leaving invalid pointers in the expectations list.
Event History
Frequently Asked Questions
What conditions are needed to trigger the use-after-free?
The issue requires Open vSwitch conntrack processing to invoke a conntrack helper that creates an expectation while the connection is still unconfirmed. Additional connection-tracking extensions must then be added, causing the extensions area to be reallocated before the expectation is removed.
How can I determine whether a system may be affected?
Review whether the running Linux kernel includes one of the referenced stable fixes, and whether the deployment uses Open vSwitch conntrack with conntrack helpers. Systems not using this processing path are not described as reaching the vulnerable sequence.
What changes after applying the fix?
Helpers are invoked only after the other extensions have been added, preventing later extension reallocation from leaving an invalid pointer in the expectations list. If helper processing is rejected, marks and labels can remain set, consistent with the prior NAT and confirmation-failure behavior.