{"dataType": "CVE_RECORD", "dataVersion": "5.2", "cveMetadata": {"cveId": "CVE-2026-74739", "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "state": "PUBLISHED", "assignerShortName": "Linux", "dateReserved": "2026-08-15T05:44:03.930Z", "datePublished": "2026-08-26T14:36:51.746Z", "dateUpdated": "2026-08-27T05:01:00.695Z"}, "containers": {"cna": {"providerMetadata": {"orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "shortName": "Linux", "dateUpdated": "2026-08-27T05:01:00.695Z"}, "descriptions": [{"lang": "en", "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nnet/sched: cls_u32: skip hash tables in u32_bind_class()\n\nu32_walk() enumerates both struct tc_u_hnode and struct tc_u_knode\nthrough the walker callback. u32_bind_class() unconditionally casts the\npassed fh to tc_u_knode and accesses &n->res, so when fh is actually a\ntc_u_hnode, which has no tcf_result member, this results in a\nslab-out-of-bounds read of res->classid in tc_cls_bind_class().\n\nThe issue can be reproduced with the following commands:\n\n tc qdisc add dev lo root handle 1: hfsc\n tc class add dev lo parent 1: classid 1:1 hfsc sc rate 1000kbit\n tc filter add dev lo parent 1:1 protocol ip prio 1 u32 match u32 0 0 flowid 1:1\n tc class add dev lo parent 1: classid 1:2 hfsc sc rate 2000kbit\n\nFix this by skipping hash tables via the TC_U32_KEY(handle) check."}], "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 - The bug is reached only via RTM_NEWTCLASS rtnetlink (tc class add) in __tc_ctl_tclass(), which calls tc_bind_tclass() to walk u32 filters; per kernel CNA guidance, tc/qdisc/netlink classifier configuration is Local, not remotely reachable by packets.\nAC:L - The reproducer is deterministic: install a u32 filter with flowid, then add another tc class so reverse binding walks hash nodes; the attacker controls every netlink step and needs no race or uncontrollable victim state.\nPR:L - RTM_NEWTCLASS requires CAP_NET_ADMIN enforced by netlink_net_capable() in rtnetlink; this capability is obtainable by unprivileged users in a user+network namespace (unshare -Urn) or containers granted NET_ADMIN, not init-namespace root only.\nUI:N - Exploitation requires only the attacker's own tc/netlink operations (qdisc, filter, class add) inside a namespace they control; no separate victim action such as opening files or mounting media is needed.\nS:U - Impact is kernel slab memory read and possible adjacent-slab corruption during tc class binding within the same host kernel; this is standard local kernel compromise, not VM escape, IOMMU bypass, or another cross-authority boundary.\nC:H - u32_bind_class() casts tc_u_hnode to tc_u_knode and reads &n->res.classid past the hnode allocation in tc_cls_bind_class(); per CNA guidance, slab out-of-bounds reads of kernel memory warrant High confidentiality impact.\nI:H - If the out-of-bounds classid read matches the newly created class, tc_cls_bind_class() calls __tcf_bind_filter(), which xchg-writes to &r->class at the bogus offset, enabling adjacent slab corruption and potential control-flow hijack per memory-corruption guidance.\nA:H - The slab out-of-bounds access is reported as a KASAN violation on trigger, and mistaken reverse binding can corrupt adjacent kernel objects leading to oops/panic during later tc operations; per CNA guidance, kernel crashes and memory corruption score Availability High."}]}], "affected": [{"product": "Linux", "vendor": "Linux", "defaultStatus": "unaffected", "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git", "programFiles": ["net/sched/cls_u32.c"], "versions": [{"version": "07d79fc7d94e3f884b8b1c95aa615b202bb5e4c1", "lessThan": "ec5f3005586a785689fd568361b0c5925cb1548b", "status": "affected", "versionType": "git"}, {"version": "07d79fc7d94e3f884b8b1c95aa615b202bb5e4c1", "lessThan": "19d114b93c94bdef70496f26685c2a6b242f41b3", "status": "affected", "versionType": "git"}, {"version": "07d79fc7d94e3f884b8b1c95aa615b202bb5e4c1", "lessThan": "594a064d603202b9ee21e07679d854e5c1750cc4", "status": "affected", "versionType": "git"}, {"version": "07d79fc7d94e3f884b8b1c95aa615b202bb5e4c1", "lessThan": "31f26a95eeee926946809ac456c61a3217936a62", "status": "affected", "versionType": "git"}, {"version": "07d79fc7d94e3f884b8b1c95aa615b202bb5e4c1", "lessThan": "e71f8e9ed6f311410b14741f6012afe01869c0fa", "status": "affected", "versionType": "git"}, {"version": "07d79fc7d94e3f884b8b1c95aa615b202bb5e4c1", "lessThan": "6d3724e616faf952c3adcf8414fc21a828ef3709", "status": "affected", "versionType": "git"}]}, {"product": "Linux", "vendor": "Linux", "defaultStatus": "affected", "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git", "programFiles": ["net/sched/cls_u32.c"], "versions": [{"version": "4.14", "status": "affected"}, {"version": "0", "lessThan": "4.14", "status": "unaffected", "versionType": "semver"}, {"version": "6.1.184", "lessThanOrEqual": "6.1.*", "status": "unaffected", "versionType": "semver"}, {"version": "6.6.153", "lessThanOrEqual": "6.6.*", "status": "unaffected", "versionType": "semver"}, {"version": "6.12.105", "lessThanOrEqual": "6.12.*", "status": "unaffected", "versionType": "semver"}, {"version": "6.18.46", "lessThanOrEqual": "6.18.*", "status": "unaffected", "versionType": "semver"}, {"version": "7.1.10", "lessThanOrEqual": "7.1.*", "status": "unaffected", "versionType": "semver"}, {"version": "7.2", "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": "4.14", "versionEndExcluding": "6.1.184"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "4.14", "versionEndExcluding": "6.6.153"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "4.14", "versionEndExcluding": "6.12.105"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "4.14", "versionEndExcluding": "6.18.46"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "4.14", "versionEndExcluding": "7.1.10"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "4.14", "versionEndExcluding": "7.2"}]}]}], "references": [{"url": "https://git.kernel.org/stable/c/ec5f3005586a785689fd568361b0c5925cb1548b"}, {"url": "https://git.kernel.org/stable/c/19d114b93c94bdef70496f26685c2a6b242f41b3"}, {"url": "https://git.kernel.org/stable/c/594a064d603202b9ee21e07679d854e5c1750cc4"}, {"url": "https://git.kernel.org/stable/c/31f26a95eeee926946809ac456c61a3217936a62"}, {"url": "https://git.kernel.org/stable/c/e71f8e9ed6f311410b14741f6012afe01869c0fa"}, {"url": "https://git.kernel.org/stable/c/6d3724e616faf952c3adcf8414fc21a828ef3709"}], "title": "net/sched: cls_u32: skip hash tables in u32_bind_class()", "x_generator": {"engine": "bippy-1.2.0"}}}}

{}

{"affected": [{"affectedData": [{"defaultStatus": "unaffected", "product": "Linux", "programFiles": ["net/sched/cls_u32.c"], "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git", "vendor": "Linux", "versions": [{"lessThan": "ec5f3005586a785689fd568361b0c5925cb1548b", "status": "affected", "version": "07d79fc7d94e3f884b8b1c95aa615b202bb5e4c1", "versionType": "git"}, {"lessThan": "19d114b93c94bdef70496f26685c2a6b242f41b3", "status": "affected", "version": "07d79fc7d94e3f884b8b1c95aa615b202bb5e4c1", "versionType": "git"}, {"lessThan": "594a064d603202b9ee21e07679d854e5c1750cc4", "status": "affected", "version": "07d79fc7d94e3f884b8b1c95aa615b202bb5e4c1", "versionType": "git"}, {"lessThan": "31f26a95eeee926946809ac456c61a3217936a62", "status": "affected", "version": "07d79fc7d94e3f884b8b1c95aa615b202bb5e4c1", "versionType": "git"}, {"lessThan": "e71f8e9ed6f311410b14741f6012afe01869c0fa", "status": "affected", "version": "07d79fc7d94e3f884b8b1c95aa615b202bb5e4c1", "versionType": "git"}, {"lessThan": "6d3724e616faf952c3adcf8414fc21a828ef3709", "status": "affected", "version": "07d79fc7d94e3f884b8b1c95aa615b202bb5e4c1", "versionType": "git"}]}, {"defaultStatus": "affected", "product": "Linux", "programFiles": ["net/sched/cls_u32.c"], "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git", "vendor": "Linux", "versions": [{"status": "affected", "version": "4.14"}, {"lessThan": "4.14", "status": "unaffected", "version": "0", "versionType": "semver"}, {"lessThanOrEqual": "6.1.*", "status": "unaffected", "version": "6.1.184", "versionType": "semver"}, {"lessThanOrEqual": "6.6.*", "status": "unaffected", "version": "6.6.153", "versionType": "semver"}, {"lessThanOrEqual": "6.12.*", "status": "unaffected", "version": "6.12.105", "versionType": "semver"}, {"lessThanOrEqual": "6.18.*", "status": "unaffected", "version": "6.18.46", "versionType": "semver"}, {"lessThanOrEqual": "7.1.*", "status": "unaffected", "version": "7.1.10", "versionType": "semver"}, {"lessThanOrEqual": "*", "status": "unaffected", "version": "7.2", "versionType": "original_commit_for_fix"}]}], "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"}], "cveTags": [], "descriptions": [{"lang": "en", "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nnet/sched: cls_u32: skip hash tables in u32_bind_class()\n\nu32_walk() enumerates both struct tc_u_hnode and struct tc_u_knode\nthrough the walker callback. u32_bind_class() unconditionally casts the\npassed fh to tc_u_knode and accesses &n->res, so when fh is actually a\ntc_u_hnode, which has no tcf_result member, this results in a\nslab-out-of-bounds read of res->classid in tc_cls_bind_class().\n\nThe issue can be reproduced with the following commands:\n\n tc qdisc add dev lo root handle 1: hfsc\n tc class add dev lo parent 1: classid 1:1 hfsc sc rate 1000kbit\n tc filter add dev lo parent 1:1 protocol ip prio 1 u32 match u32 0 0 flowid 1:1\n tc class add dev lo parent 1: classid 1:2 hfsc sc rate 2000kbit\n\nFix this by skipping hash tables via the TC_U32_KEY(handle) check."}], "id": "CVE-2026-74739", "lastModified": "2026-08-27T06:17:23.220", "metrics": {"cvssMetricV31": [{"cvssData": {"attackComplexity": "LOW", "attackVector": "LOCAL", "availabilityImpact": "HIGH", "baseScore": 7.8, "baseSeverity": "HIGH", "confidentialityImpact": "HIGH", "integrityImpact": "HIGH", "privilegesRequired": "LOW", "scope": "UNCHANGED", "userInteraction": "NONE", "vectorString": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H", "version": "3.1"}, "exploitabilityScore": 1.8, "impactScore": 5.9, "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "type": "Secondary"}]}, "published": "2026-08-26T15:16:52.603", "references": [{"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "url": "https://git.kernel.org/stable/c/19d114b93c94bdef70496f26685c2a6b242f41b3"}, {"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "url": "https://git.kernel.org/stable/c/31f26a95eeee926946809ac456c61a3217936a62"}, {"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "url": "https://git.kernel.org/stable/c/594a064d603202b9ee21e07679d854e5c1750cc4"}, {"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "url": "https://git.kernel.org/stable/c/6d3724e616faf952c3adcf8414fc21a828ef3709"}, {"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "url": "https://git.kernel.org/stable/c/e71f8e9ed6f311410b14741f6012afe01869c0fa"}, {"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "url": "https://git.kernel.org/stable/c/ec5f3005586a785689fd568361b0c5925cb1548b"}], "sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "vulnStatus": "Received"}

{}

{"affected": [{"configurations": [{"platform": null, "status": "affected", "versions": {"scheme": "code_commit", "value": "[07d79fc7d94e3f884b8b1c95aa615b202bb5e4c1,ec5f3005586a785689fd568361b0c5925cb1548b)"}}, {"platform": null, "status": "affected", "versions": {"scheme": "code_commit", "value": "[07d79fc7d94e3f884b8b1c95aa615b202bb5e4c1,19d114b93c94bdef70496f26685c2a6b242f41b3)"}}, {"platform": null, "status": "affected", "versions": {"scheme": "code_commit", "value": "[07d79fc7d94e3f884b8b1c95aa615b202bb5e4c1,594a064d603202b9ee21e07679d854e5c1750cc4)"}}, {"platform": null, "status": "affected", "versions": {"scheme": "code_commit", "value": "[07d79fc7d94e3f884b8b1c95aa615b202bb5e4c1,31f26a95eeee926946809ac456c61a3217936a62)"}}, {"platform": null, "status": "affected", "versions": {"scheme": "code_commit", "value": "[07d79fc7d94e3f884b8b1c95aa615b202bb5e4c1,e71f8e9ed6f311410b14741f6012afe01869c0fa)"}}, {"platform": null, "status": "affected", "versions": {"scheme": "code_commit", "value": "[07d79fc7d94e3f884b8b1c95aa615b202bb5e4c1,6d3724e616faf952c3adcf8414fc21a828ef3709)"}}], "enrichment": {"confidence": 99.0, "confidence_source": "inferred", "scores": [{"score": 99.0, "source": "inferred"}, {"score": 100.0, "source": "matching"}]}, "original": {"product": "Linux", "source": "cna", "vendor": "Linux"}, "product": "linux_kernel", "vendor": "linux"}, {"configurations": [{"platform": null, "status": "affected", "versions": {"scheme": "semver", "value": "4.14"}}, {"platform": null, "status": "unaffected", "versions": {"scheme": "generic", "value": "[0,4.14)"}}, {"platform": null, "status": "unaffected", "versions": {"scheme": "semver", "value": "[6.1.184,6.2.0)"}}, {"platform": null, "status": "unaffected", "versions": {"scheme": "semver", "value": "[6.6.153,6.7.0)"}}, {"platform": null, "status": "unaffected", "versions": {"scheme": "semver", "value": "[6.12.105,6.13.0)"}}, {"platform": null, "status": "unaffected", "versions": {"scheme": "semver", "value": "[6.18.46,6.19.0)"}}, {"platform": null, "status": "unaffected", "versions": {"scheme": "semver", "value": "[7.1.10,7.2.0)"}}, {"platform": null, "status": "unaffected", "versions": {"scheme": "generic", "value": "[7.2,*]"}}], "enrichment": {"confidence": 99.0, "confidence_source": "inferred", "scores": [{"score": 99.0, "source": "inferred"}, {"score": 100.0, "source": "matching"}]}, "original": {"product": "Linux", "source": "cna", "vendor": "Linux"}, "product": "linux_kernel", "vendor": "linux"}], "created": "2026-08-26T15:45:04.178734+00:00", "updated": "2026-08-26T17:00:04.698813+00:00", "vendors": ["linux", "linux$PRODUCT$linux_kernel"], "weaknesses": ["CWE-805"]}