{"id":"CVE-2026-23270","title":"net/sched: Only allow act_ct to bind to clsact/ingress qdiscs and shared blocks","summary":"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_…","severity":"high","cvss":7.8,"cvssVector":"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H","cvssSource":"cna","vendor":"Linux","product":"Linux","affected":["Linux >= 172ba7d46c202e679f3ccb10264c67416aaeb1c4 < bc4e5bb529823a09f02dbe96169de679a9db26e0","Linux >= 0b5b831122fc3789fff75be433ba3e4dd7b779d4 < fb3c380a54e33d1fd272cc342faa906d787d7ef1","Linux >= 73f7da5fd124f2cda9161e2e46114915e6e82e97 < 5a110ddcc99bda77a28598b3555fe009eaab3828","Linux >= 3f14b377d01d8357eba032b4cabc8c1149b458b6 < 524ce8b4ea8f64900b6c52b6a28df74f6bc0801e","Linux >= 3f14b377d01d8357eba032b4cabc8c1149b458b6 < 380ad8b7c65ea7aa10ef2258297079ed5ac1f5b6","Linux >= 3f14b377d01d8357eba032b4cabc8c1149b458b6 < 9deda0fcda5c1f388c5e279541850b71a2ccfcf4","Linux >= 3f14b377d01d8357eba032b4cabc8c1149b458b6 < 11cb63b0d1a0685e0831ae3c77223e002ef18189","Linux f5346df0591d10bc948761ca854b1fae6d2ef441","Linux >= 5.15.148 < 5.15.203","Linux >= 6.1.75 < 6.1.167","Linux >= 6.6.14 < 6.6.130","Linux >= 6.7.2 < 6.8","Linux 6.8"],"published":"2026-03-18","updated":"2026-09-08","sourceUpdated":"2026-09-08T08:45:13.038Z","source":"CVEORG","sourceUrl":"https://www.cve.org/CVERecord?id=CVE-2026-23270","references":[{"url":"https://git.kernel.org/stable/c/bc4e5bb529823a09f02dbe96169de679a9db26e0"},{"url":"https://git.kernel.org/stable/c/fb3c380a54e33d1fd272cc342faa906d787d7ef1"},{"url":"https://git.kernel.org/stable/c/5a110ddcc99bda77a28598b3555fe009eaab3828"},{"url":"https://git.kernel.org/stable/c/524ce8b4ea8f64900b6c52b6a28df74f6bc0801e"},{"url":"https://git.kernel.org/stable/c/380ad8b7c65ea7aa10ef2258297079ed5ac1f5b6"},{"url":"https://git.kernel.org/stable/c/9deda0fcda5c1f388c5e279541850b71a2ccfcf4"},{"url":"https://git.kernel.org/stable/c/11cb63b0d1a0685e0831ae3c77223e002ef18189"}],"tags":["cve.org"],"epss":0.00125,"epssPercentile":0.02546,"ingestedAt":"2026-09-08T15:33:26.993Z","slug":"CVE-2026-23270","body":"## Overview\n\nIn 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/\n\n## Affected\n\n- `Linux >= 172ba7d46c202e679f3ccb10264c67416aaeb1c4 < bc4e5bb529823a09f02dbe96169de679a9db26e0`\n- `Linux >= 0b5b831122fc3789fff75be433ba3e4dd7b779d4 < fb3c380a54e33d1fd272cc342faa906d787d7ef1`\n- `Linux >= 73f7da5fd124f2cda9161e2e46114915e6e82e97 < 5a110ddcc99bda77a28598b3555fe009eaab3828`\n- `Linux >= 3f14b377d01d8357eba032b4cabc8c1149b458b6 < 524ce8b4ea8f64900b6c52b6a28df74f6bc0801e`\n- `Linux >= 3f14b377d01d8357eba032b4cabc8c1149b458b6 < 380ad8b7c65ea7aa10ef2258297079ed5ac1f5b6`\n- `Linux >= 3f14b377d01d8357eba032b4cabc8c1149b458b6 < 9deda0fcda5c1f388c5e279541850b71a2ccfcf4`\n- `Linux >= 3f14b377d01d8357eba032b4cabc8c1149b458b6 < 11cb63b0d1a0685e0831ae3c77223e002ef18189`\n- `Linux f5346df0591d10bc948761ca854b1fae6d2ef441`\n- `Linux >= 5.15.148 < 5.15.203`\n- `Linux >= 6.1.75 < 6.1.167`\n- `Linux >= 6.6.14 < 6.6.130`\n- `Linux >= 6.7.2 < 6.8`\n- `Linux 6.8`\n\n## Remediation\n\nRefer to the linked advisories for vendor-supplied fixes and affected version ranges.","depth":"twilight","depthScore":43,"depthScoreParts":{"impact":42.9,"likelihood":0,"exploitation":0,"ransomware":0},"changes":[]}