{"id":"CVE-2026-23270","summary":"net/sched: Only allow act_ct to bind to clsact/ingress qdiscs and shared blocks","details":"In the Linux kernel, the following vulnerability has been resolved:\n\nnet/sched: Only allow act_ct to bind to clsact/ingress qdiscs and shared blocks\n\nAs Paolo said earlier [1]:\n\n\"Since the blamed commit below, classify can return TC_ACT_CONSUMED while\nthe current skb being held by the defragmentation engine. As reported by\nGangMin Kim, if such packet is that may cause a UaF when the defrag engine\nlater on tries to tuch again such packet.\"\n\nact_ct was never meant to be used in the egress path, however some users\nare attaching it to egress today [2]. Attempting to reach a middle\nground, we noticed that, while most qdiscs are not handling\nTC_ACT_CONSUMED, clsact/ingress qdiscs are. With that in mind, we\naddress the issue by only allowing act_ct to bind to clsact/ingress\nqdiscs and shared blocks. That way it's still possible to attach act_ct to\negress (albeit only with clsact).\n\n[1] https://lore.kernel.org/netdev/674b8cbfc385c6f37fb29a1de08d8fe5c2b0fbee.1771321118.git.pabeni@redhat.com/\n[2] https://lore.kernel.org/netdev/cc6bfb4a-4a2b-42d8-b9ce-7ef6644fb22b@ovn.org/","modified":"2026-04-02T13:12:19.385396Z","published":"2026-03-18T17:54:43.803Z","database_specific":{"osv_generated_from":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/23xxx/CVE-2026-23270.json","cna_assigner":"Linux"},"references":[{"type":"WEB","url":"https://git.kernel.org/stable/c/11cb63b0d1a0685e0831ae3c77223e002ef18189"},{"type":"WEB","url":"https://git.kernel.org/stable/c/380ad8b7c65ea7aa10ef2258297079ed5ac1f5b6"},{"type":"WEB","url":"https://git.kernel.org/stable/c/524ce8b4ea8f64900b6c52b6a28df74f6bc0801e"},{"type":"WEB","url":"https://git.kernel.org/stable/c/5a110ddcc99bda77a28598b3555fe009eaab3828"},{"type":"WEB","url":"https://git.kernel.org/stable/c/9deda0fcda5c1f388c5e279541850b71a2ccfcf4"},{"type":"WEB","url":"https://git.kernel.org/stable/c/fb3c380a54e33d1fd272cc342faa906d787d7ef1"},{"type":"ADVISORY","url":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/23xxx/CVE-2026-23270.json"},{"type":"ADVISORY","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-23270"},{"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":"0b5b831122fc3789fff75be433ba3e4dd7b779d4"},{"fixed":"fb3c380a54e33d1fd272cc342faa906d787d7ef1"}]},{"type":"GIT","repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","events":[{"introduced":"73f7da5fd124f2cda9161e2e46114915e6e82e97"},{"fixed":"5a110ddcc99bda77a28598b3555fe009eaab3828"}]},{"type":"GIT","repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","events":[{"introduced":"3f14b377d01d8357eba032b4cabc8c1149b458b6"},{"fixed":"524ce8b4ea8f64900b6c52b6a28df74f6bc0801e"},{"fixed":"380ad8b7c65ea7aa10ef2258297079ed5ac1f5b6"},{"fixed":"9deda0fcda5c1f388c5e279541850b71a2ccfcf4"},{"fixed":"11cb63b0d1a0685e0831ae3c77223e002ef18189"}]},{"type":"GIT","repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","events":[{"introduced":"0"},{"last_affected":"172ba7d46c202e679f3ccb10264c67416aaeb1c4"},{"last_affected":"f5346df0591d10bc948761ca854b1fae6d2ef441"}]}],"database_specific":{"source":"https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-23270.json"}},{"package":{"name":"Kernel","ecosystem":"Linux"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"6.1.167"}]},{"type":"ECOSYSTEM","events":[{"introduced":"6.2.0"},{"fixed":"6.6.130"}]},{"type":"ECOSYSTEM","events":[{"introduced":"6.7.0"},{"fixed":"6.12.77"}]},{"type":"ECOSYSTEM","events":[{"introduced":"6.8.0"},{"fixed":"6.18.18"}]},{"type":"ECOSYSTEM","events":[{"introduced":"6.13.0"},{"fixed":"6.19.8"}]}],"database_specific":{"source":"https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-23270.json"}}],"schema_version":"1.7.5"}