In the Linux kernel, the following vulnerability has been resolved: netfilter: conntrack: re-fetch conntrack after insertion In case the conntrack is clashing, insertion can free skb->_nfct and set skb->_nfct to the already-confirmed entry. This wasn't found before because the conntrack entry and the extension space used to free'd after an rcu grace period, plus the race needs events enabled to trigger.
https://git.kernel.org/stable/c/e97222b785e70e8973281666d709baad6523d8af
https://git.kernel.org/stable/c/b16bb373988da3ceb0308381634117e18b6ec60d
https://git.kernel.org/stable/c/92a999d1963eed0df666284e20055136ceabd12f
https://git.kernel.org/stable/c/91a36ec160ec1a0c8f5352b772dffcbb0b6023e3
https://git.kernel.org/stable/c/56b14ecec97f39118bf85c9ac2438c5a949509ed
https://git.kernel.org/stable/c/04f9e9104c969d8ce10a4a43634f641ed082092d
https://git.kernel.org/stable/c/04e4a11dc723c52db7a36dc58f0d69ce6426f8f0
https://git.kernel.org/stable/c/01989d7eebb61c99bd4b88ebc8e261bd2f02caed