{"id":"CVE-2026-74740","summary":"net/sched: act_api: fix TOCTOU NULL deref on a-\u003egoto_chain","details":"In the Linux kernel, the following vulnerability has been resolved:\n\nnet/sched: act_api: fix TOCTOU NULL deref on a-\u003egoto_chain\n\ntcf_action_exec() handles TC_ACT_GOTO_CHAIN by first checking\nrcu_access_pointer(a-\u003egoto_chain) and then calling\ntcf_action_goto_chain_exec(), which does a second, independent\nrcu_dereference_bh(a-\u003egoto_chain) read and immediately dereferences\nchain-\u003efilter_chain. A concurrent tcf_action_set_ctrlact() (e.g. the gact\nreplace path) can clear a-\u003egoto_chain between the two reads, so the second\nread returns NULL and tcf_action_goto_chain_exec() dereferences NULL.\n\nFix the race by doing a single rcu_dereference_bh() read of a-\u003egoto_chain\nin tcf_action_exec(), checking it once for NULL, and passing the resulting\nchain pointer into tcf_action_goto_chain_exec(). This turns the split\ncheck/use into a single check/use on one value.","modified":"2026-08-28T11:48:23.517111780Z","published":"2026-08-26T14:36:52.344Z","database_specific":{"cna_assigner":"Linux","osv_generated_from":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/74xxx/CVE-2026-74740.json"},"references":[{"type":"WEB","url":"https://git.kernel.org/stable/c/1ec48b6715c29b20105e3485206602cff6c51ae5"},{"type":"WEB","url":"https://git.kernel.org/stable/c/6b70886ebc428eed43a069c8944a931b5fb3f4e4"},{"type":"WEB","url":"https://git.kernel.org/stable/c/91d55fd1fdb85c8371ca8793c788ea7d5192383a"},{"type":"WEB","url":"https://git.kernel.org/stable/c/abceabc4408fca6a9dd52611f5d197dec9390d63"},{"type":"WEB","url":"https://git.kernel.org/stable/c/f60b396ee174206fe08ebf997d16cd3801b77b22"},{"type":"ADVISORY","url":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/74xxx/CVE-2026-74740.json"},{"type":"ADVISORY","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-74740"},{"type":"PACKAGE","url":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git"}],"affected":[{"ranges":[{"type":"GIT","repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","events":[{"introduced":"ee3bbfe806cdb46b02cda63626cb50a7a7b19fc5"},{"fixed":"91d55fd1fdb85c8371ca8793c788ea7d5192383a"},{"fixed":"1ec48b6715c29b20105e3485206602cff6c51ae5"},{"fixed":"abceabc4408fca6a9dd52611f5d197dec9390d63"},{"fixed":"6b70886ebc428eed43a069c8944a931b5fb3f4e4"},{"fixed":"f60b396ee174206fe08ebf997d16cd3801b77b22"}]}],"database_specific":{"source":"https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-74740.json"}},{"package":{"name":"Kernel","ecosystem":"Linux"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"5.1.0"},{"fixed":"6.6.153"}]},{"type":"ECOSYSTEM","events":[{"introduced":"6.7.0"},{"fixed":"6.12.105"}]},{"type":"ECOSYSTEM","events":[{"introduced":"6.13.0"},{"fixed":"6.18.46"}]},{"type":"ECOSYSTEM","events":[{"introduced":"6.19.0"},{"fixed":"7.1.10"}]}],"database_specific":{"source":"https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-74740.json"}}],"schema_version":"1.9.0"}