{ "dataType": "CVE_RECORD", "dataVersion": "5.2", "cveMetadata": { "cveId": "CVE-2026-23270", "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "state": "PUBLISHED", "assignerShortName": "Linux", "dateReserved": "2026-01-13T15:37:45.991Z", "datePublished": "2026-03-18T17:54:43.803Z", "dateUpdated": "2026-08-05T12:21:00.613Z" }, "containers": { "cna": { "providerMetadata": { "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "shortName": "Linux", "dateUpdated": "2026-08-05T12:21:00.613Z" }, "descriptions": [ { "lang": "en", "value": "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/" } ], "metrics": [ { "cvssV3_1": { "version": "3.1", "vectorString": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H", "baseScore": 7.8, "baseSeverity": "HIGH" }, "scenarios": [ { "lang": "en", "value": "AV:L - Exploiting this requires local access to configure tc qdiscs/filters via netlink (RTM_NEWTFILTER), which is a local operation requiring CAP_NET_ADMIN. The UaF is then triggered by sending packets through the misconfigured egress path.\nAC:L - The attacker fully controls the setup: creating the namespace, configuring the qdisc with act_ct, and sending fragmented packets to trigger defragmentation. The UaF is reliably triggered without needing to win any external race.\nPR:L - CAP_NET_ADMIN is required for tc filter creation, but this capability is obtainable by any unprivileged local user via user namespaces (unshare -Urn), making this reachable with low privileges.\nUI:N - No user interaction is needed. The attacker sets up the tc configuration and sends packets entirely on their own.\nS:U - This is a standard kernel memory corruption vulnerability. The impact stays within the kernel's security authority with no cross-boundary escape (no VM escape or sandbox escape).\nC:H - The use-after-free allows an attacker to control freed object contents via heap spraying, enabling arbitrary kernel memory reads and information disclosure.\nI:H - The use-after-free provides arbitrary write primitives through heap spraying of the freed skb, enabling code execution and full kernel compromise.\nA:H - The use-after-free causes kernel crashes (oops/panic) when the qdisc accesses the freed skb, as demonstrated in the original crash trace in the blamed commit." } ] } ], "affected": [ { "product": "Linux", "vendor": "Linux", "defaultStatus": "unaffected", "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git", "programFiles": [ "include/net/act_api.h", "net/sched/act_ct.c", "net/sched/cls_api.c" ], "versions": [ { "version": "172ba7d46c202e679f3ccb10264c67416aaeb1c4", "lessThan": "bc4e5bb529823a09f02dbe96169de679a9db26e0", "status": "affected", "versionType": "git" }, { "version": "0b5b831122fc3789fff75be433ba3e4dd7b779d4", "lessThan": "fb3c380a54e33d1fd272cc342faa906d787d7ef1", "status": "affected", "versionType": "git" }, { "version": "73f7da5fd124f2cda9161e2e46114915e6e82e97", "lessThan": "5a110ddcc99bda77a28598b3555fe009eaab3828", "status": "affected", "versionType": "git" }, { "version": "3f14b377d01d8357eba032b4cabc8c1149b458b6", "lessThan": "524ce8b4ea8f64900b6c52b6a28df74f6bc0801e", "status": "affected", "versionType": "git" }, { "version": "3f14b377d01d8357eba032b4cabc8c1149b458b6", "lessThan": "380ad8b7c65ea7aa10ef2258297079ed5ac1f5b6", "status": "affected", "versionType": "git" }, { "version": "3f14b377d01d8357eba032b4cabc8c1149b458b6", "lessThan": "9deda0fcda5c1f388c5e279541850b71a2ccfcf4", "status": "affected", "versionType": "git" }, { "version": "3f14b377d01d8357eba032b4cabc8c1149b458b6", "lessThan": "11cb63b0d1a0685e0831ae3c77223e002ef18189", "status": "affected", "versionType": "git" }, { "version": "f5346df0591d10bc948761ca854b1fae6d2ef441", "status": "affected", "versionType": "git" }, { "version": "5.15.148", "lessThan": "5.15.203", "status": "affected", "versionType": "semver" }, { "version": "6.1.75", "lessThan": "6.1.167", "status": "affected", "versionType": "semver" }, { "version": "6.6.14", "lessThan": "6.6.130", "status": "affected", "versionType": "semver" }, { "version": "6.7.2", "lessThan": "6.8", "status": "affected", "versionType": "semver" } ] }, { "product": "Linux", "vendor": "Linux", "defaultStatus": "affected", "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git", "programFiles": [ "include/net/act_api.h", "net/sched/act_ct.c", "net/sched/cls_api.c" ], "versions": [ { "version": "6.8", "status": "affected" }, { "version": "0", "lessThan": "6.8", "status": "unaffected", "versionType": "semver" }, { "version": "5.15.203", "lessThanOrEqual": "5.15.*", "status": "unaffected", "versionType": "semver" }, { "version": "6.1.167", "lessThanOrEqual": "6.1.*", "status": "unaffected", "versionType": "semver" }, { "version": "6.6.130", "lessThanOrEqual": "6.6.*", "status": "unaffected", "versionType": "semver" }, { "version": "6.12.77", "lessThanOrEqual": "6.12.*", "status": "unaffected", "versionType": "semver" }, { "version": "6.18.18", "lessThanOrEqual": "6.18.*", "status": "unaffected", "versionType": "semver" }, { "version": "6.19.8", "lessThanOrEqual": "6.19.*", "status": "unaffected", "versionType": "semver" }, { "version": "7.0", "lessThanOrEqual": "*", "status": "unaffected", "versionType": "original_commit_for_fix" } ] } ], "cpeApplicability": [ { "nodes": [ { "operator": "OR", "negate": false, "cpeMatch": [ { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "5.15.148", "versionEndExcluding": "5.15.203" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "6.1.75", "versionEndExcluding": "6.1.167" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "6.6.14", "versionEndExcluding": "6.6.130" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "6.8", "versionEndExcluding": "6.12.77" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "6.8", "versionEndExcluding": "6.18.18" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "6.8", "versionEndExcluding": "6.19.8" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "6.8", "versionEndExcluding": "7.0" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "6.7.2" } ] } ] } ], "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" } ], "title": "net/sched: Only allow act_ct to bind to clsact/ingress qdiscs and shared blocks", "x_generator": { "engine": "bippy-1.2.0" } }, "adp": [ { "x_adpType": "supplier", "providerMetadata": { "orgId": "0b142b55-0307-4c5a-b3c9-f314f3fb7c5e", "shortName": "siemens-SADP", "dateUpdated": "2026-07-14T12:46:17.247Z" }, "affected": [ { "vendor": "Siemens", "product": "SIMATIC S7-1500 CPU 1518-4 PN/DP MFP", "versions": [ { "status": "affected", "version": "V3.1.6", "lessThan": "*", 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