CVE-2026-74740
In the Linux kernel, the following vulnerability has been resolved: net/sched: act_api: fix TOCTOU NULL deref on a->goto_chain tcf_action_exec() handles TC_ACT_GOTO_CHAIN by first checking rcu_access_pointer(a->goto_chain) and then calling tcf_action_goto_chain_exec(), which does a second, independent rcu_dereference_bh(a->goto_chain) read and immediately dereferences chain->filter_chain. A concurrent tcf_action_set_ctrlact() (e.g. the gact replace path) can clear a->goto_chain between the two reads, so the second read returns NULL and tcf_action_goto_chain_exec() dereferences NULL. Fix the race by doing a single rcu_dereference_bh() read of a->goto_chain in tcf_action_exec(), checking it once for NULL, and passing the resulting chain pointer into tcf_action_goto_chain_exec(). This turns the split check/use into a single check/use on one value.
Affected versions
Linux kernel versions
5.1
and later are affected. Fixed in
6.6.153,
6.12.105,
6.18.46,
7.1.10,
7.2
and their respective stable series.
References
5 totalFrequently asked questions
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What is CVE-2026-74740?
CVE-2026-74740 is a unscored severity Linux kernel vulnerability . It affects Linux kernel versions from 5.1 onward and has been patched in 6.6.153, 6.12.105, 6.18.46 and others. CVE-2026-74740 has not been confirmed as actively exploited and is not listed in the CISA KEV catalog.
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Is there a patch available for CVE-2026-74740?
Yes. CVE-2026-74740 has been patched. Fixed versions include 6.6.153, 6.12.105, 6.18.46 and others. If you are running Linux kernel 5.1 or later up to the fix versions, apply the relevant patch for your kernel branch.
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Is CVE-2026-74740 actively exploited?
No. CVE-2026-74740 has not been confirmed as actively exploited. It is not listed in the CISA Known Exploited Vulnerabilities (KEV) catalog.