{"dataType": "CVE_RECORD", "dataVersion": "5.2", "cveMetadata": {"cveId": "CVE-2026-74663", "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "state": "PUBLISHED", "assignerShortName": "Linux", "dateReserved": "2026-08-15T05:44:03.924Z", "datePublished": "2026-08-22T15:32:35.871Z", "dateUpdated": "2026-08-27T12:39:59.404Z"}, "containers": {"cna": {"providerMetadata": {"orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "shortName": "Linux", "dateUpdated": "2026-08-27T12:39:59.404Z"}, "descriptions": [{"lang": "en", "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nnet/sched: reject overly deep qdisc hierarchies\n\nDeep qdisc hierarchies can lead to excessive recursion in qdisc tree\nwalkers and exhaust the kernel stack. The existing loop check does not\ncover the create-and-graft path, so a hierarchy can still be extended by\ncreating a new child qdisc below an already deep parent.\n\nStore the hierarchy depth in struct Qdisc and update it when qdiscs are\ngrafted. Reject new child qdiscs once the parent is already at the maximum\nallowed depth."}], "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 through RTM_NEWQDISC/tc netlink operations that build or graft qdiscs and invoke recursive qdisc tree walkers such as check_loop(); per kernel CNA guidance, tc/netlink qdisc configuration is Local and is not on any remote packet-receive path.\nAC:L - The create-and-graft path bypasses the existing depth-7 check_loop() guard, so an attacker can deterministically extend a linear classful qdisc chain (e.g., repeated HTB/HFSC grafts) and then trigger check_loop() with a graft/replace to recurse until the kernel stack is exhausted; no race or uncontrollable layout is required.\nPR:L - RTM_NEWQDISC is gated by netlink_net_capable(skb, CAP_NET_ADMIN) in rtnetlink_rcv_msg(), evaluated against the socket netns user_ns; an unprivileged local user routinely obtains CAP_NET_ADMIN via user+network namespaces (unshare -Urn) or containers with NET_ADMIN, not init-namespace root.\nUI:N - Exploitation requires only the attacker's own tc/netlink qdisc setup and a follow-on graft/replace that walks the deep hierarchy; no victim must open files, mount filesystems, click prompts, or perform any cooperative action.\nS:U - Impact is kernel-stack exhaustion and crash/panic within the same kernel security domain; it does not cross a VM, IOMMU, or sandbox boundary to another security authority such as guest-to-host escape.\nC:H - Unbounded recursion in qdisc tree walkers overflows the kernel task stack and corrupts stack memory before the guard-page fault; under overestimation guidance, such stack corruption is treated as plausibly enabling kernel memory disclosure rather than a pure crash with no data exposure.\nI:H - Recursive stack exhaustion overwrites saved return addresses and adjacent kernel stack frames, providing a plausible path to control-flow hijack or arbitrary kernel modification even though the immediate failure mode is oops/panic, not a bounded integrity change.\nA:H - Excessive recursion in qdisc tree walkers exhausts the kernel stack and causes a kernel oops/panic, denying all system availability on the host until reboot; any kernel stack guard fault or panic from this path scores Availability High."}]}], "affected": [{"product": "Linux", "vendor": "Linux", "defaultStatus": "unaffected", "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git", "programFiles": ["include/net/sch_generic.h", "net/sched/sch_api.c"], "versions": [{"version": "1da177e4c3f41524e886b7f1b8a0c1fc7321cac2", "lessThan": "08dc49df1527b09d9ea225a7265bbf6c237097bf", "status": "affected", "versionType": "git"}, {"version": "1da177e4c3f41524e886b7f1b8a0c1fc7321cac2", "lessThan": "a627d36c2a94e18c8c105ae68008786dfd85592e", "status": "affected", "versionType": "git"}, {"version": "1da177e4c3f41524e886b7f1b8a0c1fc7321cac2", "lessThan": "9f69bb9fdaa2fe64b68bb62fb84d405784bee540", "status": "affected", "versionType": "git"}, {"version": "1da177e4c3f41524e886b7f1b8a0c1fc7321cac2", "lessThan": "8ca8cdb74939581339e1ae370193c0adb5a85336", "status": "affected", "versionType": "git"}, {"version": "1da177e4c3f41524e886b7f1b8a0c1fc7321cac2", "lessThan": "2759acf08a3454866660edcd3ef4e64139f254a6", "status": "affected", "versionType": "git"}, {"version": "1da177e4c3f41524e886b7f1b8a0c1fc7321cac2", "lessThan": "a4b14a4df29d36458a943f9b521ddd0f940363cc", "status": "affected", "versionType": "git"}, {"version": "1da177e4c3f41524e886b7f1b8a0c1fc7321cac2", "lessThan": "e2d658c6427844cee5bc654b436ca68d680b6148", "status": "affected", "versionType": "git"}, {"version": "1da177e4c3f41524e886b7f1b8a0c1fc7321cac2", "lessThan": "dedd34b0f2310e28c5f6d4875cfbf4b7ed821c01", "status": "affected", "versionType": "git"}]}, {"product": "Linux", "vendor": "Linux", "defaultStatus": "affected", "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git", "programFiles": ["include/net/sch_generic.h", "net/sched/sch_api.c"], "versions": [{"version": "2.6.12", "status": "affected"}, {"version": "0", "lessThan": "2.6.12", "status": "unaffected", "versionType": "semver"}, {"version": "5.10.267", "lessThanOrEqual": "5.10.*", "status": "unaffected", "versionType": "semver"}, {"version": "5.15.218", "lessThanOrEqual": "5.15.*", "status": "unaffected", "versionType": "semver"}, {"version": "6.1.183", "lessThanOrEqual": "6.1.*", "status": "unaffected", "versionType": "semver"}, {"version": "6.6.152", "lessThanOrEqual": "6.6.*", "status": "unaffected", "versionType": "semver"}, {"version": "6.12.104", "lessThanOrEqual": "6.12.*", "status": "unaffected", "versionType": "semver"}, {"version": "6.18.45", "lessThanOrEqual": "6.18.*", "status": "unaffected", "versionType": "semver"}, {"version": "7.1.9", "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": "2.6.12", "versionEndExcluding": "5.10.267"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "2.6.12", "versionEndExcluding": "5.15.218"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "2.6.12", "versionEndExcluding": "6.1.183"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "2.6.12", "versionEndExcluding": "6.6.152"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "2.6.12", "versionEndExcluding": "6.12.104"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "2.6.12", "versionEndExcluding": "6.18.45"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "2.6.12", "versionEndExcluding": "7.1.9"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "2.6.12", "versionEndExcluding": "7.2"}]}]}], "references": [{"url": "https://git.kernel.org/stable/c/08dc49df1527b09d9ea225a7265bbf6c237097bf"}, {"url": "https://git.kernel.org/stable/c/a627d36c2a94e18c8c105ae68008786dfd85592e"}, {"url": "https://git.kernel.org/stable/c/9f69bb9fdaa2fe64b68bb62fb84d405784bee540"}, {"url": "https://git.kernel.org/stable/c/8ca8cdb74939581339e1ae370193c0adb5a85336"}, {"url": "https://git.kernel.org/stable/c/2759acf08a3454866660edcd3ef4e64139f254a6"}, {"url": "https://git.kernel.org/stable/c/a4b14a4df29d36458a943f9b521ddd0f940363cc"}, {"url": "https://git.kernel.org/stable/c/e2d658c6427844cee5bc654b436ca68d680b6148"}, {"url": "https://git.kernel.org/stable/c/dedd34b0f2310e28c5f6d4875cfbf4b7ed821c01"}], "title": "net/sched: reject overly deep qdisc hierarchies", "x_generator": {"engine": "bippy-1.2.0"}}}}

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{"affected": [{"affectedData": [{"defaultStatus": "unaffected", "product": "Linux", "programFiles": ["include/net/sch_generic.h", "net/sched/sch_api.c"], "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git", "vendor": "Linux", "versions": [{"lessThan": "08dc49df1527b09d9ea225a7265bbf6c237097bf", "status": "affected", "version": "1da177e4c3f41524e886b7f1b8a0c1fc7321cac2", "versionType": "git"}, {"lessThan": "a627d36c2a94e18c8c105ae68008786dfd85592e", "status": "affected", "version": "1da177e4c3f41524e886b7f1b8a0c1fc7321cac2", "versionType": "git"}, {"lessThan": "9f69bb9fdaa2fe64b68bb62fb84d405784bee540", "status": "affected", "version": "1da177e4c3f41524e886b7f1b8a0c1fc7321cac2", "versionType": "git"}, {"lessThan": "8ca8cdb74939581339e1ae370193c0adb5a85336", "status": "affected", "version": "1da177e4c3f41524e886b7f1b8a0c1fc7321cac2", "versionType": "git"}, {"lessThan": "2759acf08a3454866660edcd3ef4e64139f254a6", "status": "affected", "version": "1da177e4c3f41524e886b7f1b8a0c1fc7321cac2", "versionType": "git"}, {"lessThan": "a4b14a4df29d36458a943f9b521ddd0f940363cc", "status": "affected", "version": "1da177e4c3f41524e886b7f1b8a0c1fc7321cac2", "versionType": "git"}, {"lessThan": "e2d658c6427844cee5bc654b436ca68d680b6148", "status": "affected", "version": "1da177e4c3f41524e886b7f1b8a0c1fc7321cac2", "versionType": "git"}, {"lessThan": "dedd34b0f2310e28c5f6d4875cfbf4b7ed821c01", "status": "affected", "version": "1da177e4c3f41524e886b7f1b8a0c1fc7321cac2", "versionType": "git"}]}, {"defaultStatus": "affected", "product": "Linux", "programFiles": ["include/net/sch_generic.h", "net/sched/sch_api.c"], "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git", "vendor": "Linux", "versions": [{"status": "affected", "version": "2.6.12"}, {"lessThan": "2.6.12", "status": "unaffected", "version": "0", "versionType": "semver"}, {"lessThanOrEqual": "5.10.*", "status": "unaffected", "version": "5.10.267", "versionType": "semver"}, {"lessThanOrEqual": "5.15.*", "status": "unaffected", "version": "5.15.218", "versionType": "semver"}, {"lessThanOrEqual": "6.1.*", "status": "unaffected", "version": "6.1.183", "versionType": "semver"}, {"lessThanOrEqual": "6.6.*", "status": "unaffected", "version": "6.6.152", "versionType": "semver"}, {"lessThanOrEqual": "6.12.*", "status": "unaffected", "version": "6.12.104", "versionType": "semver"}, {"lessThanOrEqual": "6.18.*", "status": "unaffected", "version": "6.18.45", "versionType": "semver"}, {"lessThanOrEqual": "7.1.*", "status": "unaffected", "version": "7.1.9", "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: reject overly deep qdisc hierarchies\n\nDeep qdisc hierarchies can lead to excessive recursion in qdisc tree\nwalkers and exhaust the kernel stack. The existing loop check does not\ncover the create-and-graft path, so a hierarchy can still be extended by\ncreating a new child qdisc below an already deep parent.\n\nStore the hierarchy depth in struct Qdisc and update it when qdiscs are\ngrafted. Reject new child qdiscs once the parent is already at the maximum\nallowed depth."}], "id": "CVE-2026-74663", "lastModified": "2026-08-27T13:18:36.473", "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": "2026-08-22T16:16:40.103", "references": [{"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "url": "https://git.kernel.org/stable/c/08dc49df1527b09d9ea225a7265bbf6c237097bf"}, {"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "url": "https://git.kernel.org/stable/c/2759acf08a3454866660edcd3ef4e64139f254a6"}, {"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "url": "https://git.kernel.org/stable/c/8ca8cdb74939581339e1ae370193c0adb5a85336"}, {"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "url": "https://git.kernel.org/stable/c/9f69bb9fdaa2fe64b68bb62fb84d405784bee540"}, {"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "url": "https://git.kernel.org/stable/c/a4b14a4df29d36458a943f9b521ddd0f940363cc"}, {"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "url": "https://git.kernel.org/stable/c/a627d36c2a94e18c8c105ae68008786dfd85592e"}, {"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "url": "https://git.kernel.org/stable/c/dedd34b0f2310e28c5f6d4875cfbf4b7ed821c01"}, {"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "url": "https://git.kernel.org/stable/c/e2d658c6427844cee5bc654b436ca68d680b6148"}], "sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "vulnStatus": "Received"}

{"bugzilla": {"description": "kernel: net/sched: reject overly deep qdisc hierarchies", "id": "2521389", "url": "https://bugzilla.redhat.com/show_bug.cgi?id=2521389"}, "csaw": false, "cvss3": {"cvss3_base_score": "5.5", "cvss3_scoring_vector": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H", "status": "draft"}, "cwe": "CWE-770", "details": ["A flaw was found in the Linux kernel. An attacker could create overly deep queueing discipline (qdisc) hierarchies, leading to excessive recursion in qdisc tree walkers. This can exhaust the kernel stack, resulting in a Denial of Service (DoS) due to a system crash."], "name": "CVE-2026-74663", "public_date": "2026-08-22T00:00:00Z", "references": ["https://www.cve.org/CVERecord?id=CVE-2026-74663\nhttps://nvd.nist.gov/vuln/detail/CVE-2026-74663\nhttps://lore.kernel.org/linux-cve-announce/2026082228-CVE-2026-74663-88a3@gregkh/T"], "threat_severity": "Moderate"}