CVE-2026-74663 (GCVE-0-2026-74663)
Vulnerability from cvelistv5 – Published: 2026-08-22 15:32 – Updated: 2026-10-16 19:16
VLAI
EPSS
VEX
Title
net/sched: reject overly deep qdisc hierarchies
Summary
In the Linux kernel, the following vulnerability has been resolved:
net/sched: reject overly deep qdisc hierarchies
Deep qdisc hierarchies can lead to excessive recursion in qdisc tree
walkers and exhaust the kernel stack. The existing loop check does not
cover the create-and-graft path, so a hierarchy can still be extended by
creating a new child qdisc below an already deep parent.
Store the hierarchy depth in struct Qdisc and update it when qdiscs are
grafted. Reject new child qdiscs once the parent is already at the maximum
allowed depth.
Severity
7.8 (High)
SSVC
Exploitation: none
Automatable: no
Technical Impact: total
CISA Coordinator · CISA-ADP (v2.0.3)
Decision recorded 2026-10-16 19:14 UTC
Assigner
References
8 references
Impacted products
2 products
| Vendor | Product | Version | CPE status | |
|---|---|---|---|---|
| Linux | Linux |
Affected:
1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 , < 08dc49df1527b09d9ea225a7265bbf6c237097bf
(git)
Affected: 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 , < a627d36c2a94e18c8c105ae68008786dfd85592e (git) Affected: 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 , < 9f69bb9fdaa2fe64b68bb62fb84d405784bee540 (git) Affected: 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 , < 8ca8cdb74939581339e1ae370193c0adb5a85336 (git) Affected: 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 , < 2759acf08a3454866660edcd3ef4e64139f254a6 (git) Affected: 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 , < a4b14a4df29d36458a943f9b521ddd0f940363cc (git) Affected: 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 , < e2d658c6427844cee5bc654b436ca68d680b6148 (git) Affected: 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 , < dedd34b0f2310e28c5f6d4875cfbf4b7ed821c01 (git) |
guessed | |
| Linux | Linux |
Affected:
2.6.12
Unaffected: 0 , < 2.6.12 (semver) Unaffected: 5.10.267 , ≤ 5.10.* (semver) Unaffected: 5.15.218 , ≤ 5.15.* (semver) Unaffected: 6.1.183 , ≤ 6.1.* (semver) Unaffected: 6.6.152 , ≤ 6.6.* (semver) Unaffected: 6.12.104 , ≤ 6.12.* (semver) Unaffected: 6.18.45 , ≤ 6.18.* (semver) Unaffected: 7.1.9 , ≤ 7.1.* (semver) Unaffected: 7.2 , ≤ * (original_commit_for_fix) |
guessed |
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"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."
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"lang": "es",
"value": "En el kernel de Linux, la siguiente vulnerabilidad ha sido resuelta:\n\nnet/sched: rechazar jerarqu\u00edas de qdisc excesivamente profundas\n\nLas jerarqu\u00edas de qdisc profundas pueden llevar a una recursi\u00f3n excesiva en los \u0027qdisc tree walkers\u0027 y agotar la pila del kernel. La comprobaci\u00f3n de bucle existente no cubre la ruta de creaci\u00f3n e injerto, por lo que una jerarqu\u00eda a\u00fan puede extenderse creando un nuevo qdisc hijo debajo de un padre ya profundo.\n\nAlmacenar la profundidad de la jerarqu\u00eda en \u0027struct Qdisc\u0027 y actualizarla cuando los qdiscs son injertados. Rechazar nuevos qdiscs hijos una vez que el padre ya est\u00e1 en la profundidad m\u00e1xima permitida."
}
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"id": "CVE-2026-74663",
"lastModified": "2026-10-16T20:17:50.400",
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"scope": "UNCHANGED",
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{
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"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"
}
},
"redhat_vex": {
"aggregate_severity": "Low",
"current_release_date": "2026-10-17T21:44:30+00:00",
"cve": "CVE-2026-74663",
"id": "CVE-2026-74663",
"initial_release_date": "2026-08-22T00:00:00+00:00",
"product_status:known_affected": "275",
"source": "Red Hat CSAF VEX",
"status": "final",
"title": "kernel: net/sched: reject overly deep qdisc hierarchies",
"url": "https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-74663.json",
"version": "3"
},
"vulnrichment": {
"containers": {
"adp": [
{
"metrics": [
{
"other": {
"content": {
"id": "CVE-2026-74663",
"options": [
{
"Exploitation": "none"
},
{
"Automatable": "no"
},
{
"Technical Impact": "total"
}
],
"role": "CISA Coordinator",
"timestamp": "2026-10-16T19:14:09.885396Z",
"version": "2.0.3"
},
"type": "ssvc"
}
}
],
"providerMetadata": {
"dateUpdated": "2026-10-16T19:14:10.483Z",
"orgId": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
"shortName": "CISA-ADP"
},
"title": "CISA ADP Vulnrichment"
}
],
"cna": {
"affected": [
{
"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",
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},
{
"lessThan": "8ca8cdb74939581339e1ae370193c0adb5a85336",
"status": "affected",
"version": "1da177e4c3f41524e886b7f1b8a0c1fc7321cac2",
"versionType": "git"
},
{
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"status": "affected",
"version": "1da177e4c3f41524e886b7f1b8a0c1fc7321cac2",
"versionType": "git"
},
{
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"versionType": "git"
},
{
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"status": "affected",
"version": "1da177e4c3f41524e886b7f1b8a0c1fc7321cac2",
"versionType": "git"
},
{
"lessThan": "dedd34b0f2310e28c5f6d4875cfbf4b7ed821c01",
"status": "affected",
"version": "1da177e4c3f41524e886b7f1b8a0c1fc7321cac2",
"versionType": "git"
}
]
},
{
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"product": "Linux",
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"repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
"vendor": "Linux",
"versions": [
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"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"
}
]
}
],
"cpeApplicability": [
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"nodes": [
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"versionEndExcluding": "5.10.267",
"versionStartIncluding": "2.6.12",
"vulnerable": true
},
{
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"versionEndExcluding": "5.15.218",
"versionStartIncluding": "2.6.12",
"vulnerable": true
},
{
"criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
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},
{
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"versionEndExcluding": "6.12.104",
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"vulnerable": true
},
{
"criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
"versionEndExcluding": "6.18.45",
"versionStartIncluding": "2.6.12",
"vulnerable": true
},
{
"criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
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}
],
"negate": false,
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}
],
"descriptions": [
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"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": {
"baseScore": 7.8,
"baseSeverity": "HIGH",
"vectorString": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H",
"version": "3.1"
},
"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\u0027s 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."
}
]
}
],
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{
"url": "https://git.kernel.org/stable/c/a627d36c2a94e18c8c105ae68008786dfd85592e"
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{
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},
{
"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": {
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}
}
},
"cveMetadata": {
"assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"assignerShortName": "Linux",
"cveId": "CVE-2026-74663",
"datePublished": "2026-08-22T15:32:35.871Z",
"dateReserved": "2026-08-15T05:44:03.924Z",
"dateUpdated": "2026-10-16T19:16:07.950Z",
"state": "PUBLISHED"
},
"dataType": "CVE_RECORD",
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}
}
}
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Drag nodes to arrange them. Double-click a related vulnerability to open it, or a source to visit its link. The Physics button on the left tunes the layout and the simulation; the legend at the bottom left hides or shows nodes by kind and by sighting type.
Experimental. This forecast is provided for visualization only and may change without notice. Do not use it for operational decisions.
Forecast uses a logistic model when the trend is rising, or an exponential decay model when the trend is falling. Fitted via linearized least squares.
Sightings
| Author | Source | Type | Date | Other |
|---|
Nomenclature
- Seen: The vulnerability was mentioned, discussed, or observed by the user.
- Confirmed: The vulnerability has been validated from an analyst's perspective.
- Published Proof of Concept: A public proof of concept is available for this vulnerability.
- Exploited: The vulnerability was observed as exploited by the user who reported the sighting.
- Patched: The vulnerability was observed as successfully patched by the user who reported the sighting.
- Not exploited: The vulnerability was not observed as exploited by the user who reported the sighting.
- Not confirmed: The user expressed doubt about the validity of the vulnerability.
- Not patched: The vulnerability was not observed as successfully patched by the user who reported the sighting.
Vulnerability timeline
Sightings and recorded dates, grouped by day · UTC
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The MITRE ATT&CK techniques below are AI-generated suggestions, inferred from the description of the
vulnerability by the CIRCL/vulnerability-attack-technique-classification-roberta-base
model, served locally by ML-Gateway.
They have not been verified by an analyst and are provided for guidance only.
The approach is described in our paper Mapping CVEs to MITRE ATT&CK Techniques: A Curated Gold-Set Classifier and the Limits of LLM-Assisted Label Expansion.
Browse all ATT&CK techniques and the vulnerabilities related to each.
The approach is described in our paper Mapping CVEs to MITRE ATT&CK Techniques: A Curated Gold-Set Classifier and the Limits of LLM-Assisted Label Expansion.
Browse all ATT&CK techniques and the vulnerabilities related to each.
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Related by attack behaviour
Vulnerabilities whose description is nearest to this one in the vector space of the CIRCL/vulnerability-attack-technique-biencoder model. This is a similarity search over the bi-encoder space (plain cosine), not a classification, and it has no measured accuracy.